9ce56f91c0
Up until now, an initialized MpegEncContext had an array of MPVPictures (way more than were ever needed) and the MPVPicture* contained in the MPVWorkPictures as well as the input_picture and reordered_input_picture arrays (for the encoder) pointed into this array. Several of the pointers could point to the same slot and because there was no reference counting involved, one had to check for aliasing before unreferencing. Furthermore, given that these pointers were not ownership pointers the pointers were often simply reset without unreferencing the slot (happened e.g. for the RV30 and RV40 decoders) or there were moved without resetting the src pointer (happened for the encoders where the entries in the input_picture and reordered_input_picture arrays were not reset). Instead actually releasing these pictures was performed by looping over the whole array and checking which one of the entries needed to be kept. Given that the array had way too many slots (36), this meant that more than 30 MPVPictures have been unnecessarily unreferenced in every ff_mpv_frame_start(); something similar happened for the encoder. This commit changes this by making the MPVPictures refcounted via the RefStruct API. The MPVPictures itself are part of a pool so that this does not entail constant allocations; instead, the amount of allocations actually goes down, because the earlier code used such a large array of MPVPictures (36 entries) and allocated an AVFrame for every one of these on every ff_mpv_common_init(). In fact, the pool is only freed when closing the codec, so that reinitializations don't lead to new allocations (this avoids having to sync the pool in update_thread_context). Making MPVPictures refcounted also has another key benefit: It makes it possible to directly share them across threads (when using frame-threaded decoding), eliminating ugly code with underlying av_frame_ref()'s; sharing these pictures can't fail any more. The pool is allocated in ff_mpv_decode_init() for decoders, which therefore can fail now. This and the fact that the pool is not unreferenced in ff_mpv_common_end() also necessitated to mark several mpegvideo-decoders with the FF_CODEC_CAP_INIT_CLEANUP flag. *: This also means that there is no good reason any more for ff_mpv_common_frame_size_change() to exist. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
FFmpeg README
FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.
Libraries
libavcodecprovides implementation of a wider range of codecs.libavformatimplements streaming protocols, container formats and basic I/O access.libavutilincludes hashers, decompressors and miscellaneous utility functions.libavfilterprovides means to alter decoded audio and video through a directed graph of connected filters.libavdeviceprovides an abstraction to access capture and playback devices.libswresampleimplements audio mixing and resampling routines.libswscaleimplements color conversion and scaling routines.
Tools
- ffmpeg is a command line toolbox to manipulate, convert and stream multimedia content.
- ffplay is a minimalistic multimedia player.
- ffprobe is a simple analysis tool to inspect multimedia content.
- Additional small tools such as
aviocat,ismindexandqt-faststart.
Documentation
The offline documentation is available in the doc/ directory.
The online documentation is available in the main website and in the wiki.
Examples
Coding examples are available in the doc/examples directory.
License
FFmpeg codebase is mainly LGPL-licensed with optional components licensed under GPL. Please refer to the LICENSE file for detailed information.
Contributing
Patches should be submitted to the ffmpeg-devel mailing list using
git format-patch or git send-email. Github pull requests should be
avoided because they are not part of our review process and will be ignored.