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GStreamer multimedia framework
2762ead5ef
This allows: * Better duration estimation * More accurate PCR location * Overall more accurate running-time location and calculation Location and values of PCR are recorded in groups (PCROffsetGroup) with notable PCR/Offset observations in them (when bitrate changed for example). PCR and offset are stored as 32bit values to reduce memory usage (they are differences against that group's first_{pcr|offset}. Those groups each contain a global PCR offset (pcr_offset) which indicates how far in the stream that group is. Whenever new PCR values are observed, we store them in a sliding window estimator (PCROffsetGroupCurrent). When a reset/wrapover/gap is detected, we close the current group with current values and start a new one (the pcr_offset of that new group is also calculated). When a notable change in bitrate is observed (+/- 10%), we record new values in the current group. This is a compromise between storing all PCR/offset observations and none, while at the same time providing better information for running-time<=>offset calculation in VBR streams. Whenever a new non-contiguous group is start (due to seeking for example) we re-evaluate the pcr_offset of each groups. This allows detecting as quickly as possible PCR wrapover/reset. When wanting to find the offset of a certain running-time, one can iterate the groups by looking at the pcr_offset (which in essence *is* the running-time of that group in the overall stream). Once a group (or neighbouring groups if the running-time is between two groups) is found, once can use the recorded values to find the most accurate offset. Right now this code is only used in pull-mode , but could also be activated later on for any seekable stream, like live timeshift with queue2. Future improvements: * some heuristics to "compress" the stored values in groups so as to keep the memory usage down while still keeping a decent amount of notable points. * After a seek compare expected and obtained PCR/Offset and if the difference is too big, re-calculate position with newly observed values and seek to that more accurate position. Note that this code will *not* provide keyframe-accurate seeking, but will allow a much more accurate PCR/running-time/offset location on any random stream. For past (observed) values it will be as accurate as can be. For future values it will be better than the current situation. Finally the more you seek, the more accurate your positioning will be. |
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gst-plugins-bad.doap | ||
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Makefile.am | ||
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GStreamer 1.3.x development series WHAT IT IS ---------- This is GStreamer, a framework for streaming media. WHERE TO START -------------- We have a website at http://gstreamer.freedesktop.org/ You should start by going through our FAQ at http://gstreamer.freedesktop.org/data/doc/gstreamer/head/faq/html/ There is more documentation; go to http://gstreamer.freedesktop.org/documentation You can subscribe to our mailing lists; see the website for details. We track bugs in GNOME's bugzilla; see the website for details. You can join us on IRC - #gstreamer on irc.freenode.org GStreamer 1.0 series -------------------- Starring GSTREAMER The core around which all other modules revolve. Base functionality and libraries, some essential elements, documentation, and testing. BASE A well-groomed and well-maintained collection of GStreamer plug-ins and elements, spanning the range of possible types of elements one would want to write for GStreamer. And introducing, for the first time ever, on the development screen ... THE GOOD --- "Such ingratitude. After all the times I've saved your life." A collection of plug-ins you'd want to have right next to you on the battlefield. Shooting sharp and making no mistakes, these plug-ins have it all: good looks, good code, and good licensing. Documented and dressed up in tests. If you're looking for a role model to base your own plug-in on, here it is. If you find a plot hole or a badly lip-synced line of code in them, let us know - it is a matter of honour for us to ensure Blondie doesn't look like he's been walking 100 miles through the desert without water. THE UGLY --- "When you have to shoot, shoot. Don't talk." There are times when the world needs a color between black and white. Quality code to match the good's, but two-timing, backstabbing and ready to sell your freedom down the river. These plug-ins might have a patent noose around their neck, or a lock-up license, or any other problem that makes you think twice about shipping them. We don't call them ugly because we like them less. Does a mother love her son less because he's not as pretty as the other ones ? No - she commends him on his great personality. These plug-ins are the life of the party. And we'll still step in and set them straight if you report any unacceptable behaviour - because there are two kinds of people in the world, my friend: those with a rope around their neck and the people who do the cutting. THE BAD --- "That an accusation?" No perfectly groomed moustache or any amount of fine clothing is going to cover up the truth - these plug-ins are Bad with a capital B. They look fine on the outside, and might even appear to get the job done, but at the end of the day they're a black sheep. Without a golden-haired angel to watch over them, they'll probably land in an unmarked grave at the final showdown. Don't bug us about their quality - exercise your Free Software rights, patch up the offender and send us the patch on the fastest steed you can steal from the Confederates. Because you see, in this world, there's two kinds of people, my friend: those with loaded guns and those who dig. You dig. The Lowdown ----------- --- "I've never seen so many plug-ins wasted so badly." GStreamer Plug-ins has grown so big that it's hard to separate the wheat from the chaff. Also, distributors have brought up issues about the legal status of some of the plug-ins we ship. To remedy this, we've divided the previous set of available plug-ins into four modules: - gst-plugins-base: a small and fixed set of plug-ins, covering a wide range of possible types of elements; these are continuously kept up-to-date with any core changes during the development series. - We believe distributors can safely ship these plug-ins. - People writing elements should base their code on these elements. - These elements come with examples, documentation, and regression tests. - gst-plugins-good: a set of plug-ins that we consider to have good quality code, correct functionality, our preferred license (LGPL for the plug-in code, LGPL or LGPL-compatible for the supporting library). - We believe distributors can safely ship these plug-ins. - People writing elements should base their code on these elements. - gst-plugins-ugly: a set of plug-ins that have good quality and correct functionality, but distributing them might pose problems. The license on either the plug-ins or the supporting libraries might not be how we'd like. The code might be widely known to present patent problems. - Distributors should check if they want/can ship these plug-ins. - People writing elements should base their code on these elements. - gst-plugins-bad: a set of plug-ins that aren't up to par compared to the rest. They might be close to being good quality, but they're missing something - be it a good code review, some documentation, a set of tests, a real live maintainer, or some actual wide use. If the blanks are filled in they might be upgraded to become part of either gst-plugins-good or gst-plugins-ugly, depending on the other factors. - If the plug-ins break, you can't complain - instead, you can fix the problem and send us a patch, or bribe someone into fixing them for you. - New contributors can start here for things to work on. PLATFORMS --------- - Linux is of course fully supported - FreeBSD is reported to work; other BSDs should work too - Solaris is reported to work; a specific sunaudiosink plugin has been written - MacOSX works, binary 1.x packages can be built using the cerbero build tool - Windows works; binary 1.x packages can be built using the cerbero build tool - MSys/MinGW builds - Microsoft Visual Studio builds are not yet available or supported - Android works, binary 1.x packages can be built using the cerbero build tool - iOS works INSTALLING FROM PACKAGES ------------------------ You should always prefer installing from packages first. GStreamer is well-maintained for a number of distributions, including Fedora, Debian, Ubuntu, Mandrake, Gentoo, ... Only in cases where you: - want to hack on GStreamer - want to verify that a bug has been fixed - do not have a sane distribution should you choose to build from source tarballs or git. Find more information about the various packages at http://gstreamer.freedesktop.org/download/ COMPILING FROM SOURCE TARBALLS ------------------------------ - again, make sure that you really need to install from source ! If GStreamer is one of your first projects ever that you build from source, consider taking on an easier project. - check output of ./configure --help to see if any options apply to you - run ./configure make to build GStreamer. - if you want to install it (not required, but what you usually want to do), run make install - try out a simple test: gst-launch -v fakesrc num_buffers=5 ! fakesink (If you didn't install GStreamer, prefix gst-launch with tools/) If it outputs a bunch of messages from fakesrc and fakesink, everything is ok. If it did not work, keep in mind that you might need to adjust the PATH and/or LD_LIBRARY_PATH environment variables to make the system find GStreamer in the prefix where you installed (by default that is /usr/local). - After this, you're ready to install gst-plugins, which will provide the functionality you're probably looking for by now, so go on and read that README. COMPILING FROM GIT ------------------ When building from git sources, you will need to run autogen.sh to generate the build system files. You will need a set of additional tools typical for building from git, including: - autoconf - automake - libtool autogen.sh will check for recent enough versions and complain if you don't have them. You can also specify specific versions of automake and autoconf with --with-automake and --with-autoconf Check autogen.sh options by running autogen.sh --help autogen.sh can pass on arguments to configure When you have done this once, you can use autoregen.sh to re-autogen with the last passed options as a handy shortcut. Use it. After the autogen.sh stage, you can follow the directions listed in "COMPILING FROM SOURCE" You can also run your whole git stack uninstalled in your home directory, so that you can quickly test changes without affecting your system setup or interfering with GStreamer installed from packages. Many GStreamer developers use an uninstalled setup for their work. There is a 'create-uninstalled-setup.sh' script in http://cgit.freedesktop.org/gstreamer/gstreamer/tree/scripts/ to easily create an uninstalled setup from scratch. PLUG-IN DEPENDENCIES AND LICENSES --------------------------------- GStreamer is developed under the terms of the LGPL (see LICENSE file for details). Some of our plug-ins however rely on libraries which are available under other licenses. This means that if you are distributing an application which has a non-GPL compatible license (for instance a closed-source application) with GStreamer, you have to make sure not to distribute GPL-linked plug-ins. When using GPL-linked plug-ins, GStreamer is for all practical reasons under the GPL itself. HISTORY ------- The fundamental design comes from the video pipeline at Oregon Graduate Institute, as well as some ideas from DirectMedia. It's based on plug-ins that will provide the various codec and other functionality. The interface hopefully is generic enough for various companies (ahem, Apple) to release binary codecs for Linux, until such time as they get a clue and release the source.