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docs/design: Add encoding/profile proposal/design
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Edward Hervey
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106
docs/design/encoding-research.txt
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docs/design/encoding-research.txt
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GStreamer: Research into encoding and muxing
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--------------------------------------------
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Use Cases
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---------
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This is a list of various use-cases where encoding/muxing is being
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used.
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* Transcoding
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The goal is to convert with as minimal loss of quality any input
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file for a target use.
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A specific variant of this is transmuxing (see below).
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Example applications: Arista, Transmageddon
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* Rendering timelines
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The incoming streams are a collection of various segments that need
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to be rendered.
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Those segments can vary in nature (i.e. the video width/height can
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change).
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This requires the use of identiy with the single-segment property
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activated to transform the incoming collection of segments to a
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single continuous segment.
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Example applications: PiTiVi, Jokosher
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* Encoding of live sources
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The major risk to take into account is the encoder not encoding the
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incoming stream fast enough. This is outside of the scope of
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encodebin, and should be solved by using queues between the sources
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and encodebin, as well as implementing QoS in encoders and sources
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(the encoders emitting QoS events, and the upstream elements
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adapting themselves accordingly).
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Example applications: camerabin, cheese
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* Screencasting applications
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This is similar to encoding of live sources.
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The difference being that due to the nature of the source (size and
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amount/frequency of updates) one might want to do the encoding in
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two parts:
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* The actual live capture is encoded with a 'almost-lossless' codec
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(such as huffyuv)
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* Once the capture is done, the file created in the first step is
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then rendered to the desired target format.
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Fixing sources to only emit region-updates and having encoders
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capable of encoding those streams would fix the need for the first
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step but is outside of the scope of encodebin.
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Example applications: Istanbul, gnome-shell, recordmydesktop
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* Live transcoding
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This is the case of an incoming live stream which will be
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broadcasted/transmitted live.
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One issue to take into account is to reduce the encoding latency to
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a minimum. This should mostly be done by picking low-latency
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encoders.
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Example applications: Rygel, Coherence
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* Transmuxing
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Given a certain file, the aim is to remux the contents WITHOUT
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decoding into either a different container format or the same
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container format.
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Remuxing into the same container format is useful when the file was
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not created properly (for example, the index is missing).
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Whenever available, parsers should be applied on the encoded streams
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to validate and/or fix the streams before muxing them.
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Metadata from the original file must be kept in the newly created
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file.
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Example applications: Arista, Transmaggedon
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* Loss-less cutting
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Given a certain file, the aim is to extract a certain part of the
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file without going through the process of decoding and re-encoding
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that file.
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This is similar to the transmuxing use-case.
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Example applications: PiTiVi, Transmageddon, Arista, ...
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* Multi-pass encoding
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Some encoders allow doing a multi-pass encoding.
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The initial pass(es) are only used to collect encoding estimates and
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are not actually muxed and outputted.
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The final pass uses previously collected information, and the output
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is then muxed and outputted.
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* CD ripping
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Example applications: Sound-juicer
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* DVD ripping
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docs/design/encoding.txt
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docs/design/encoding.txt
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Encoding and Muxing
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-------------------
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Summary
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-------
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0 Problems
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0 Goals
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1. EncodeBin
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2. Encoding Profile System
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3. Helper Library for Profiles
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0. Problems this proposal attempts to solve
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-------------------------------------------
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* Duplication of pipeline code for gstreamer-based applications
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wishing to encode and or mux streams, leading to subtle differences
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and inconsistencies accross those applications.
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* No unified system for describing encoding targets for applications
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in a user-friendly way.
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* No unified system for creating encoding targets for applications,
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resulting in duplication of code accross all applications,
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differences and inconsistencies that come with that duplication.
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0. Goals
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--------
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1. Convenience encoding element
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Create a convenience GstBin for encoding and muxing several streams,
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hereafter called 'EncodeBin'.
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This element will only contain one single property, which is a
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profile.
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2. Define a encoding profile system
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2. Encoding profile helper library
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Create a helper library to:
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* create EncodeBin instances based on profiles, and
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* help applications to create/load/save those profiles.
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1. EncodeBin
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------------
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1.1 Proposed API
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----------------
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EncodeBin is a GstBin subclass.
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It implements the GstTagSetter interface, by which it will proxy the
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calls to the muxer.
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Only two introspectable property (i.e. usable without extra API):
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* A GstEncodingProfile*
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* The name of the profile to use
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When a profile is selected, encodebin will:
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* Add REQUEST sinkpads for all the GstStreamProfile
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* Create the muxer and expose the source pad
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Whenever a request pad is created, encodebin will:
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* Create the chain of elements for that pad
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* Ghost the sink pad
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* Return that ghost pad
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This allows reducing the code to the minimum for applications
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wishing to encode a source for a given profile:
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...
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encbin = gst_element_factory_make("encodebin, NULL);
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g_object_set (encbin, "profile", "N900/H264 HQ", NULL);
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gst_element_link (encbin, filesink);
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...
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vsrcpad = gst_element_get_src_pad(source, "src1");
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vsinkpad = gst_element_get_request_pad (encbin, "video_%d");
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gst_pad_link(vsrcpad, vsinkpad);
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...
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1.2 Explanation of the Various stages in EncodeBin
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--------------------------------------------------
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This describes the various stages which can happen in order to end
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up with a multiplexed stream that can then be stored or streamed.
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1.2.1 Incoming streams
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The streams fed to EncodeBin can be of various types:
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* Video
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* Uncompressed (but maybe subsampled)
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* Compressed
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* Audio
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* Uncompressed (audio/x-raw-{int|float})
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* Compressed
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* Timed text
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* Private streams
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1.2.2 Steps involved for raw video encoding
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(0) Incoming Stream
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(1) Transform raw video feed (optional)
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Here we modify the various fundamental properties of a raw video
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stream to be compatible with the intersection of:
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* The encoder GstCaps and
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* The specified "Stream Restriction" of the profile/target
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The fundamental properties that can be modified are:
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* width/height
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This is done with a video scaler.
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The DAR (Display Aspect Ratio) MUST be respected.
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If needed, black borders can be added to comply with the target DAR.
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* framerate
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* format/colorspace/depth
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All of this is done with a colorspace converter
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(2) Actual encoding (optional for raw streams)
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An encoder (with some optional settings) is used.
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(3) Muxing
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A muxer (with some optional settings) is used.
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(4) Outgoing encoded and muxed stream
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1.2.3 Steps involved for raw audio encoding
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This is roughly the same as for raw video, expect for (1)
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(1) Transform raw audo feed (optional)
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We modify the various fundamental properties of a raw audio stream to
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be compatible with the intersection of:
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* The encoder GstCaps and
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* The specified "Stream Restriction" of the profile/target
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The fundamental properties that can be modifier are:
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* Number of channels
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* Type of raw audio (integer or floating point)
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* Depth (number of bits required to encode one sample)
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1.2.4 Steps involved for encoded audio/video streams
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Steps (1) and (2) are replaced by a parser if a parser is available
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for the given format.
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1.2.5 Steps involved for other streams
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Other streams will just be forwarded as-is to the muxer, provided the
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muxer accepts the stream type.
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2. Encoding Profile System
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--------------------------
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This work is based on:
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* The existing GstPreset system for elements [0]
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* The gnome-media GConf audio profile system [1]
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* The investigation done into device profiles by Arista and
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Transmageddon [2 and 3]
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2.2 Terminology
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---------------
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* Encoding Target Category
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A Target Category is a classification of devices/systems/use-cases
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for encoding.
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Such a classification is required in order for:
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* Applications with a very-specific use-case to limit the number of
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profiles they can offer the user. A screencasting application has no
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use with the online services targets for example.
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* Offering the user some initial classification in the case of a
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more generic encoding application (like a video editor or a
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transcoder).
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Ex:
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Consumer devices
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Online service
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Intermediate editing format
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Screencast
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Capture
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Computer
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* Encoding Profile Target
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A Profile Target describes a specific entity for which we wish to
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encode.
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A Profile Target must belong to at least one Target Category.
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It will define at least one Encoding Profile.
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Ex (with category):
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Nokia N900 (Consumer device)
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Sony PlayStation 3 (Consumer device)
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Youtube (Online service)
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DNxHD (Intermediate editing format)
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HuffYUV (Screencast)
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Theora (Computer)
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* Encoding Profile
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A specific combination of muxer, encoders, presets and limitations.
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Ex:
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Nokia N900/H264 HQ
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Ipod/High Quality
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DVD/Pal
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Youtube/High Quality
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HTML5/Low Bandwith
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DNxHD
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2.3 Encoding Profile
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--------------------
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An encoding profile requires the following information:
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* Name
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This string is not translatable and must be unique.
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A recommendation to guarantee uniqueness of the naming could be:
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<target>/<name>
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* Description
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This is a translatable string describing the profile
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* Muxing format
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This is a string containing the GStreamer mime-type of the
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container format.
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* Muxing preset
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This is an optional string describing the preset(s) to use on the
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muxer.
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* Multipass setting
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This is a boolean describing whether the profile requires several
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passes.
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* List of Stream Profile
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2.3.1 Stream Profiles
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A Stream Profile consists of:
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* Type
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The type of stream profile (audio, video, text, private-data)
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* Encoding Format
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This is a string containing the GStreamer mime-type of the encoding
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format to be used. If encoding is not to be applied, the raw audio
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mime type will be used.
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* Encoding preset
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This is an optional string describing the preset(s) to use on the
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encoder.
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* Restriction
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This is an optional GstCaps containing the restriction of the
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stream that can be fed to the encoder.
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This will generally containing restrictions in video
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width/heigh/framerate or audio depth.
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* presence
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This is an integer specifying how many streams can be used in the
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containing profile. 0 means that any number of streams can be
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used.
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* pass
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This is an integer which is only meaningful if the multipass flag
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has been set in the profile. If it has been set it indicates which
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pass this Stream Profile corresponds to.
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2.4 Example profile
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-------------------
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The representation used here is XML only as an example. No decision is
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made as to which formatting to use for storing targets and profiles.
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<gst-encoding-target>
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<name>Nokia N900</name>
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<category>Consumer Device</category>
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<profiles>
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<profile>Nokia N900/H264 HQ</profile>
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<profile>Nokia N900/MP3</profile>
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<profile>Nokia N900/AAC</profile>
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</profiles>
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</gst-encoding-target>
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<gst-encoding-profile>
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<name>Nokia N900/H264 HQ</name>
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<description>
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High Quality H264/AAC for the Nokia N900
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</description>
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<format>video/quicktime,variant=iso</format>
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<streams>
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<stream-profile>
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<type>audio</type>
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<format>audio/mpeg,mpegversion=4</format>
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<preset>Quality High/Main</preset>
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<restriction>audio/x-raw-int,channels=[1,2]</restriction>
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<presence>1</presence>
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</stream-profile>
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<stream-profile>
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<type>video</type>
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<format>video/x-h264</format>
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<preset>Profile Baseline/Quality High</preset>
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<restriction>
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video/x-raw-yuv,width=[16, 800],\
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height=[16, 480],framerate=[1/1, 30000/1001]
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</restriction>
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<presence>1</presence>
|
||||||
|
</stream-profile>
|
||||||
|
</streams>
|
||||||
|
|
||||||
|
</gst-encoding-profile>
|
||||||
|
|
||||||
|
2.5 API
|
||||||
|
-------
|
||||||
|
A proposed C API is contained in the gstprofile.h file in this directory.
|
||||||
|
|
||||||
|
|
||||||
|
2.6 Modifications required in the existing GstPreset system
|
||||||
|
-----------------------------------------------------------
|
||||||
|
|
||||||
|
2.6.1. Temporary preset.
|
||||||
|
|
||||||
|
Currently a preset needs to be saved on disk in order to be
|
||||||
|
used.
|
||||||
|
|
||||||
|
This makes it impossible to have temporary presets (that exist only
|
||||||
|
during the lifetime of a process), which might be required in the
|
||||||
|
new proposed profile system
|
||||||
|
|
||||||
|
2.6.2 Categorisation of presets.
|
||||||
|
|
||||||
|
Currently presets are just aliases of a group of property/value
|
||||||
|
without any meanings or explanation as to how they exclude each
|
||||||
|
other.
|
||||||
|
|
||||||
|
Take for example the H264 encoder. It can have presets for:
|
||||||
|
* passes (1,2 or 3 passes)
|
||||||
|
* profiles (Baseline, Main, ...)
|
||||||
|
* quality (Low, medium, High)
|
||||||
|
|
||||||
|
In order to programmatically know which presets exclude each other,
|
||||||
|
we here propose the categorisation of these presets.
|
||||||
|
|
||||||
|
This can be done in one of two ways
|
||||||
|
1. in the name (by making the name be [<category>:]<name>)
|
||||||
|
This would give for example: "Quality:High", "Profile:Baseline"
|
||||||
|
2. by adding a new _meta key
|
||||||
|
This would give for example: _meta/category:quality
|
||||||
|
|
||||||
|
2.6.3 Aggregation of presets.
|
||||||
|
|
||||||
|
There can be more than one choice of presets to be done for an
|
||||||
|
element (quality, profile, pass).
|
||||||
|
|
||||||
|
This means that one can not currently describe the full
|
||||||
|
configuration of an element with a single string but with many.
|
||||||
|
|
||||||
|
The proposal here is to extend the GstPreset API to be able to set
|
||||||
|
all presets using one string and a well-known separator ('/').
|
||||||
|
|
||||||
|
This change only requires changes in the core preset handling code.
|
||||||
|
|
||||||
|
This would allow doing the following:
|
||||||
|
gst_preset_load_preset (h264enc,
|
||||||
|
"pass:1/profile:baseline/quality:high");
|
||||||
|
|
||||||
|
|
||||||
|
3. Helper library for profiles
|
||||||
|
------------------------------
|
||||||
|
|
||||||
|
These helper methods could also be added to existing libraries (like
|
||||||
|
GstPreset, GstPbUtils, ..).
|
||||||
|
|
||||||
|
The various API proposed are in the accompanying gstprofile.h file.
|
||||||
|
|
||||||
|
3.1 Getting user-readable names for formats
|
||||||
|
|
||||||
|
This is already provided by GstPbUtils.
|
||||||
|
|
||||||
|
3.2 Hierarchy of profiles
|
||||||
|
|
||||||
|
The goal is for applications to be able to present to the user a list
|
||||||
|
of combo-boxes for choosing their output profile:
|
||||||
|
|
||||||
|
[ Category ] # optional, depends on the application
|
||||||
|
[ Device/Site/.. ] # optional, depends on the application
|
||||||
|
[ Profile ]
|
||||||
|
|
||||||
|
Convenience methods are offered to easily get lists of categories,
|
||||||
|
devices, and profiles.
|
||||||
|
|
||||||
|
3.3 Creating Profiles
|
||||||
|
|
||||||
|
The goal is for applications to be able to easily create profiles.
|
||||||
|
|
||||||
|
The applications needs to be able to have a fast/efficient way to:
|
||||||
|
* select a container format and see all compatible streams he can use
|
||||||
|
with it.
|
||||||
|
* select a codec format and see which container formats he can use
|
||||||
|
with it.
|
||||||
|
|
||||||
|
The remaining parts concern the restrictions to encoder
|
||||||
|
input.
|
||||||
|
|
||||||
|
|
||||||
|
[0] http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPreset.html
|
||||||
|
[1] http://www.gnome.org/~bmsmith/gconf-docs/C/gnome-media.html
|
||||||
|
[2] http://gstreamer.freedesktop.org/wiki/DeviceProfile
|
||||||
|
[3] http://gstreamer.freedesktop.org/wiki/PresetDesign
|
||||||
|
|
||||||
46
docs/design/gstencodebin.h
Normal file
46
docs/design/gstencodebin.h
Normal file
|
|
@ -0,0 +1,46 @@
|
||||||
|
/* GStreamer encoding bin
|
||||||
|
* Copyright (C) 2009 Edward Hervey <edward.hervey@collabora.co.uk>
|
||||||
|
* (C) 2009 Nokia Corporation
|
||||||
|
*
|
||||||
|
* This library is free software; you can redistribute it and/or
|
||||||
|
* modify it under the terms of the GNU Library General Public
|
||||||
|
* License as published by the Free Software Foundation; either
|
||||||
|
* version 2 of the License, or (at your option) any later version.
|
||||||
|
*
|
||||||
|
* This library is distributed in the hope that it will be useful,
|
||||||
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||||
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||||
|
* Library General Public License for more details.
|
||||||
|
*
|
||||||
|
* You should have received a copy of the GNU Library General Public
|
||||||
|
* License along with this library; if not, write to the
|
||||||
|
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
||||||
|
* Boston, MA 02111-1307, USA.
|
||||||
|
*/
|
||||||
|
|
||||||
|
#ifndef __GST_ENCODEBIN_H__
|
||||||
|
#define __GST_ENCODEBIN_H__
|
||||||
|
|
||||||
|
#include <gst/gst.h>
|
||||||
|
#include <gst/gstprofile.h>
|
||||||
|
|
||||||
|
#define GST_TYPE_ENCODE_BIN (gst_encode_bin_get_type())
|
||||||
|
#define GST_ENCODE_BIN(obj) (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_ENCODE_BIN,GstPlayBin))
|
||||||
|
#define GST_ENCODE_BIN_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_ENCODE_BIN,GstPlayBinClass))
|
||||||
|
#define GST_IS_ENCODE_BIN(obj) (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_ENCODE_BIN))
|
||||||
|
#define GST_IS_ENCODE_BIN_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_ENCODE_BIN))
|
||||||
|
|
||||||
|
typedef struct _GstEncodebin GstEncodeBin;
|
||||||
|
|
||||||
|
struct _GstEncodeBin {
|
||||||
|
GstBin parent;
|
||||||
|
|
||||||
|
GstProfile *profile;
|
||||||
|
};
|
||||||
|
|
||||||
|
GType gst_encode_bin_get_type(void);
|
||||||
|
|
||||||
|
GstElement *gst_encode_bin_new (GstProfile *profile, gchar *name);
|
||||||
|
gboolean gst_encode_bin_set_profile (GstEncodeBin *ebin, GstProfile *profile);
|
||||||
|
|
||||||
|
#endif __GST_ENCODEBIN_H__
|
||||||
219
docs/design/gstprofile.h
Normal file
219
docs/design/gstprofile.h
Normal file
|
|
@ -0,0 +1,219 @@
|
||||||
|
/* GStreamer encoding profiles library
|
||||||
|
* Copyright (C) 2009 Edward Hervey <edward.hervey@collabora.co.uk>
|
||||||
|
* (C) 2009 Nokia Corporation
|
||||||
|
*
|
||||||
|
* This library is free software; you can redistribute it and/or
|
||||||
|
* modify it under the terms of the GNU Library General Public
|
||||||
|
* License as published by the Free Software Foundation; either
|
||||||
|
* version 2 of the License, or (at your option) any later version.
|
||||||
|
*
|
||||||
|
* This library is distributed in the hope that it will be useful,
|
||||||
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||||
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||||||
|
* Library General Public License for more details.
|
||||||
|
*
|
||||||
|
* You should have received a copy of the GNU Library General Public
|
||||||
|
* License along with this library; if not, write to the
|
||||||
|
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
||||||
|
* Boston, MA 02111-1307, USA.
|
||||||
|
*/
|
||||||
|
|
||||||
|
#ifndef __GST_PROFILE_H__
|
||||||
|
#define __GST_PROFILE_H__
|
||||||
|
|
||||||
|
#include <gst/gst.h>
|
||||||
|
|
||||||
|
typedef enum {
|
||||||
|
GST_ENCODING_PROFILE_VIDEO,
|
||||||
|
GST_ENCODING_PROFILE_AUDIO,
|
||||||
|
GST_ENCODING_PROFILE_TEXT,
|
||||||
|
GST_ENCODING_PROFILE_UNKNOWN
|
||||||
|
} GstEncodingProfileType;
|
||||||
|
|
||||||
|
typedef struct _GstEncodingTarget GstEncodingTarget;
|
||||||
|
typedef struct _GstEncodingProfile GstEncodingProfile;
|
||||||
|
typedef struct _GstStreamEncodingProfile GstStreamEncodingProfile;
|
||||||
|
typedef struct _GstVideoEncodingProfile GstVideoEncodingProfile;
|
||||||
|
|
||||||
|
/* FIXME/UNKNOWNS
|
||||||
|
*
|
||||||
|
* Should encoding categories be well-known strings/quarks ?
|
||||||
|
*
|
||||||
|
*/
|
||||||
|
|
||||||
|
/**
|
||||||
|
* GstEncodingTarget:
|
||||||
|
* @name: The name of the target profile.
|
||||||
|
* @category: The target category (device, service, use-case).
|
||||||
|
* @profiles: A list of #GstProfile this device supports.
|
||||||
|
*
|
||||||
|
*/
|
||||||
|
struct _GstEncodingTarget {
|
||||||
|
gchar *name;
|
||||||
|
gchar *category;
|
||||||
|
GList *profiles;
|
||||||
|
}
|
||||||
|
|
||||||
|
/**
|
||||||
|
* GstEncodingProfile:
|
||||||
|
* @name: The name of the profile
|
||||||
|
* @format: The GStreamer mime type corresponding to the muxing format.
|
||||||
|
* @preset: The name of the #GstPreset(s) to be used on the muxer. This is optional.
|
||||||
|
* @multipass: Whether this profile is a multi-pass profile or not.
|
||||||
|
* @encodingprofiles: A list of #GstStreamEncodingProfile for the various streams.
|
||||||
|
*
|
||||||
|
*/
|
||||||
|
|
||||||
|
struct _GstEncodingProfile {
|
||||||
|
gchar *name;
|
||||||
|
gchar *format;
|
||||||
|
gchar *preset;
|
||||||
|
gboolean multipass;
|
||||||
|
GList *encodingprofiles;
|
||||||
|
};
|
||||||
|
|
||||||
|
/**
|
||||||
|
* GstStreamEncodingProfile:
|
||||||
|
* @type: Type of profile
|
||||||
|
* @format: The GStreamer mime type corresponding to the encoding format.
|
||||||
|
* @preset: The name of the #GstPreset to be used on the encoder. This is optional.
|
||||||
|
* @restriction: The #GstCaps restricting the input. This is optional.
|
||||||
|
* @presence: The number of streams that can be created. 0 => any.
|
||||||
|
*/
|
||||||
|
struct _GstStreamEncodingProfile {
|
||||||
|
GstEncodingProfileType type;
|
||||||
|
gchar *format;
|
||||||
|
gchar *preset;
|
||||||
|
GstCaps *restriction;
|
||||||
|
guint presence;
|
||||||
|
};
|
||||||
|
|
||||||
|
/**
|
||||||
|
* GstVideoEncodingProfile:
|
||||||
|
* @profile: common #GstEncodingProfile part.
|
||||||
|
* @pass: The pass number if this is part of a multi-pass profile. Starts at 1
|
||||||
|
* for multi-pass. Set to 0 if this is not part of a multi-pass profile.
|
||||||
|
*/
|
||||||
|
struct _GstVideoEncodingProfile {
|
||||||
|
GstStreamEncodingProfile profile;
|
||||||
|
guint pass;
|
||||||
|
};
|
||||||
|
|
||||||
|
/* Generic helper API */
|
||||||
|
/**
|
||||||
|
* gst_encoding_category_list_target:
|
||||||
|
* @category: a profile target category name. Can be NULL.
|
||||||
|
*
|
||||||
|
* Returns the list of all available #GstProfileTarget for the given @category.
|
||||||
|
* If @category is #NULL, then all available #GstProfileTarget are returned.
|
||||||
|
*/
|
||||||
|
GList *gst_encoding_category_list_target (gchar *category);
|
||||||
|
|
||||||
|
/**
|
||||||
|
* list available profile target categories
|
||||||
|
*/
|
||||||
|
GList *gst_profile_list_target_categories ();
|
||||||
|
|
||||||
|
gboolean gst_profile_target_save (GstProfileTarget *target);
|
||||||
|
|
||||||
|
|
||||||
|
/*
|
||||||
|
* Application convenience methods (possibly to be added in gst-pb-utils)
|
||||||
|
*/
|
||||||
|
|
||||||
|
/**
|
||||||
|
* gst_pb_utils_create_encoder:
|
||||||
|
* @caps: The #GstCaps corresponding to a codec format
|
||||||
|
* @preset: The name of a preset
|
||||||
|
* @name: The name to give to the returned instance, can be #NULL.
|
||||||
|
*
|
||||||
|
* Creates an encoder which can output the given @caps. If several encoders can
|
||||||
|
* output the given @caps, then the one with the highest rank will be picked.
|
||||||
|
* If a @preset is specified, it will be applied to the created encoder before
|
||||||
|
* returning it.
|
||||||
|
* If a @preset is specified, then the highest-ranked encoder that can accept
|
||||||
|
* the givein preset will be returned.
|
||||||
|
*
|
||||||
|
* Returns: The encoder instance with the preset applied if it is available.
|
||||||
|
* #NULL if no encoder is available.
|
||||||
|
*/
|
||||||
|
GstElement *gst_pb_utils_create_encoder(GstCaps *caps, gchar *preset, gchar *name);
|
||||||
|
/**
|
||||||
|
* gst_pb_utils_create_encoder_format:
|
||||||
|
*
|
||||||
|
* Convenience version of @gst_pb_utils_create_encoder except one does not need
|
||||||
|
* to create a #GstCaps.
|
||||||
|
*/
|
||||||
|
GstElement *gst_pb_utils_create_encoder_format(gchar *format, gchar *preset,
|
||||||
|
gchar *name);
|
||||||
|
|
||||||
|
/**
|
||||||
|
* gst_pb_utils_create_muxer:
|
||||||
|
* @caps: The #GstCaps corresponding to a codec format
|
||||||
|
* @preset: The name of a preset
|
||||||
|
*
|
||||||
|
* Creates an muxer which can output the given @caps. If several muxers can
|
||||||
|
* output the given @caps, then the one with the highest rank will be picked.
|
||||||
|
* If a @preset is specified, it will be applied to the created muxer before
|
||||||
|
* returning it.
|
||||||
|
* If a @preset is specified, then the highest-ranked muxer that can accept
|
||||||
|
* the givein preset will be returned.
|
||||||
|
*
|
||||||
|
* Returns: The muxer instance with the preset applied if it is available.
|
||||||
|
* #NULL if no muxer is available.
|
||||||
|
*/
|
||||||
|
GstElement *gst_pb_utils_create_muxer(GstCaps *caps, gchar *preset);
|
||||||
|
/**
|
||||||
|
* gst_pb_utils_create_muxer_format:
|
||||||
|
*
|
||||||
|
* Convenience version of @gst_pb_utils_create_muxer except one does not need
|
||||||
|
* to create a #GstCaps.
|
||||||
|
*/
|
||||||
|
GstElement *gst_pb_utils_create_muxer_format(gchar *format, gchar *preset,
|
||||||
|
gchar *name);
|
||||||
|
|
||||||
|
/**
|
||||||
|
* gst_pb_utils_encoders_compatible_with_muxer:
|
||||||
|
* @muxer: a muxer instance
|
||||||
|
*
|
||||||
|
* Finds a list of available encoders whose output can be fed to the given
|
||||||
|
* @muxer.
|
||||||
|
*
|
||||||
|
* Returns: A list of compatible encoders, or #NULL if none can be found.
|
||||||
|
*/
|
||||||
|
GList *gst_pb_utils_encoders_compatible_with_muxer(GstElement *muxer);
|
||||||
|
|
||||||
|
GList *gst_pb_utils_muxers_compatible_with_encoder(GstElement *encoder);
|
||||||
|
|
||||||
|
|
||||||
|
/*
|
||||||
|
* GstPreset modifications
|
||||||
|
*/
|
||||||
|
|
||||||
|
/**
|
||||||
|
* gst_preset_create:
|
||||||
|
* @preset: The #GstPreset on which to create the preset
|
||||||
|
* @name: A name for the preset
|
||||||
|
* @properties: The properties
|
||||||
|
*
|
||||||
|
* Creates a new preset with the given properties. This preset will only
|
||||||
|
* exist during the lifetime of the process.
|
||||||
|
* If you wish to use it after the lifetime of the process, you must call
|
||||||
|
* @gst_preset_save_preset.
|
||||||
|
*
|
||||||
|
* Returns: #TRUE if the preset could be created, else #FALSE.
|
||||||
|
*/
|
||||||
|
gboolean gst_preset_create (GstPreset *preset, gchar *name,
|
||||||
|
GstStructure *properties);
|
||||||
|
|
||||||
|
/**
|
||||||
|
* gst_preset_reset:
|
||||||
|
* @preset: a #GstPreset
|
||||||
|
*
|
||||||
|
* Sets all the properties of the element back to their default values.
|
||||||
|
*/
|
||||||
|
/* FIXME : This could actually be put at the GstObject level, or maybe even
|
||||||
|
* at the GObject leve. */
|
||||||
|
void gst_preset_reset (GstPreset *preset);
|
||||||
|
|
||||||
|
#endif /* __GST_PROFILE_H__ */
|
||||||
Loading…
Reference in a new issue