This is to avoid having to create a reference chain in decoders from
GstVideoCodecFrame to GstH264PIcture to implementation wrapper.
So this change introduces:
- gst_h264_dpb_remove_outputed (dpb)
- gst_h264_dpb_get_picture(dpb, system_frame_num)
- gst_h264_decoder_get_picture (dec, system_frame_num)
In order to ensure that frames can be looked up during the draining
process, we now first remove all (including reference) frames that
have been outputed but are still in the DPB. Then for each remaining
buffers, we remove it from the DPB to reach reference 1 and output it.
Previously we could take all not outputed outside of the DPB which would
prevent lookup by the base class.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1449>
... when gst_video_decoder_finish_frame() is called.
Some subclasses attach GstBuffer to GstH264Picture as an user data
which will increase reference count of the buffer. It would result
to buffer copy per every frame.
Background here is, GstVideoDecoder wants writable output buffer for
GstMeta handling, and if the output buffer is not writable
(i.e., reference count is not one), the buffer will be copied.
Even if underlying GstMemory wouldn't be copied, buffer copy operation
will introduce extra memory allocation overhead which is not optimal.
By this modification, subclass might be able to receive the last
reference to GstH264Picture
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1449>
All subclasses are retrieving list to get target output frame, which
can be done by baseclass. And pass the ownership of the GstH264Picture
to subclass so that subclass can clear implementation dependent resources
before finishing the frame.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1449>
There are some streams, with HRD, where the the calculated
max_dpb_frames is zero (max_dpb_mbs is less than size mb). In order to
get the dbp size it is required to rely on the VUI parameters if they
are present.
According to the spec Annex E.2.1
**max_dec_frame_buffering** specifies the required size of the HRD
decoded picture buffer (DPB) in units of frame buffers. It is a
requirement of bitstream conformance that the coded video sequence
shall not require a decoded picture buffer with size of more than
Max(1, max_dec_frame_buffering) frame buffers to enable the output of
decoded pictures at the output times specified by dpb_output_delay of
the picture timing SEI messages. The value of max_dec_frame_buffering
shall be greater than or equal to max_num_ref_frames. An upper bound
for the value of max_dec_frame_buffering is specified by the level
limits in clauses A.3.1, A.3.2, G.10.2.1, and H.10.2.
When the max_dec_frame_buffering syntax element is not present, the
value of max_dec_frame_buffering shall be inferred as follows:
– If profile_idc is equal to 44, 86, 100, 110, 122, or 244 and
constraint_set3_flag is equal to 1, the value of
max_dec_frame_buffering shall be inferred to be equal to 0.
– Otherwise (profile_idc is not equal to 44, 86, 100, 110, 122, or 244
or constraint_set3_flag is equal to 0), the value of
max_dec_frame_buffering shall be inferred to be equal to MaxDpbFrames.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1381>
Using glist requires a lot of small allocation at runtime and also
it comes with a slow sort algorithm. As we play with that for very
frame and slices, use GArray instead. Note that we cache some arrays
in the instance as there is no support for stack allocated arrays
in GArray.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1238>
In case of IDR, any previously decoded pictures must be drained
before the IDR and POC of IDR should be zero. So we can output
IDR immediately. Also, when POC of current picture is expected to be
the next output POC, decoder can output the picture as well
without waiting.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1211>
... to prevent requesting decoding before the preparation.
For instance, baseclass should not request decoding a picture if there
is no parsed valid headers, since subclass is most likely
not ready to decoding it.
As per specification in A.3.1 h) and A.3.2 f), the maximum size of the DPB is
16. Fix the maximum in the fine and fix the formula to use MIN instead of MAX
so that we no longer always use the maximum for the profile/level.
If decoding failed because end_picture() failed, set the picture to
nonexisting, this way output_picture() will be skipped. This avoids confusing
special cases in output_picture() implementation.
See C.5.2.2 Output and removal of pictures from the DPB.
If the number of pictures in the DPB is greater than or equal to
sps_max_dec_pic_buffering_minus1[HighestTid] + 1, then the picture
should be outputted.
On new_segment, the decoder is expected to negotiate. The decoder may want to
pre-allocate the needed buffers. Pass the max_dpb_size as this is needed to
determin how many buffers should be allocated.
This introduce a library which contains a set of base classes which
handles the parsing and the state tracking for the purpose of decoding
different CODECs. Currently H264, H265 and VP9 are supported. These
bases classes are used to decode with low level decoding API like DXVA,
NVDEC, VDPAU, VAAPI and V4L2 State Less decoders. The new library is
named gstreamer-codecs-1.0 / libgstcodecs.
