FFmpeg

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Author	SHA1	Message	Date
Anton Khirnov	587081a179	fftools/ffmpeg: use the sync queues to handle -frames Same issues apply to it as to -shortest. Changes the results of the following tests: - matroska-flac-extradata-update The test reencodes two input FLAC streams into three output FLAC streams. The last output stream is limited to 8 frames. The current code results in the first two output streams having 12 frames, after this commit all three streams have 8 frames and are the same length. This new result is better, since it is predictable. - mkv-1242 The test streamcopies one video and one audio stream, video is limited to 11 frames. The new result shortens the audio stream so that it is not longer than the video.	3 years ago
Anton Khirnov	4740fea7dd	fftools/ffmpeg: rework -shortest implementation The -shortest option (which finishes the output file at the time the shortest stream ends) is currently implemented by faking the -t option when an output stream ends. This approach is fragile, since it depends on the frames/packets being processed in a specific order. E.g. there are currently some situations in which the output file length will depend unpredictably on unrelated factors like encoder delay. More importantly, the present work aiming at splitting various ffmpeg components into different threads will make this approach completely unworkable, since the frames/packets will arrive in effectively random order. This commit introduces a "sync queue", which is essentially a collection of FIFOs, one per stream. Frames/packets are submitted to these FIFOs and are then released for further processing (encoding or muxing) when it is ensured that the frame in question will not cause its stream to get ahead of the other streams (the logic is similar to libavformat's interleaving queue). These sync queues are then used for encoding and/or muxing when the -shortest option is specified. A new option – -shortest_buf_duration – controls the maximum number of queued packets, to avoid runaway memory usage. This commit changes the results of the following tests: - copy-shortest[12]: the last audio frame is now gone. This is correct, since it actually outlasts the last video frame. - shortest-sub: the video packets following the last subtitle packet are now gone. This is also correct.	3 years ago

Author

SHA1

Message

Date

Anton Khirnov

587081a179

fftools/ffmpeg: use the sync queues to handle -frames

Same issues apply to it as to -shortest.

Changes the results of the following tests:
- matroska-flac-extradata-update
  The test reencodes two input FLAC streams into three output FLAC
  streams. The last output stream is limited to 8 frames. The current
  code results in the first two output streams having 12 frames, after
  this commit all three streams have 8 frames and are the same length.
  This new result is better, since it is predictable.
- mkv-1242
  The test streamcopies one video and one audio stream, video is limited
  to 11 frames. The new result shortens the audio stream so that it is
  not longer than the video.

3 years ago

Anton Khirnov

4740fea7dd

fftools/ffmpeg: rework -shortest implementation

The -shortest option (which finishes the output file at the time the
shortest stream ends) is currently implemented by faking the -t option
when an output stream ends. This approach is fragile, since it depends
on the frames/packets being processed in a specific order. E.g. there
are currently some situations in which the output file length will
depend unpredictably on unrelated factors like encoder delay. More
importantly, the present work aiming at splitting various ffmpeg
components into different threads will make this approach completely
unworkable, since the frames/packets will arrive in effectively random
order.

This commit introduces a "sync queue", which is essentially a collection
of FIFOs, one per stream. Frames/packets are submitted to these FIFOs
and are then released for further processing (encoding or muxing) when
it is ensured that the frame in question will not cause its stream to
get ahead of the other streams (the logic is similar to libavformat's
interleaving queue).

These sync queues are then used for encoding and/or muxing when the
-shortest option is specified.

A new option – -shortest_buf_duration – controls the maximum number of
queued packets, to avoid runaway memory usage.

This commit changes the results of the following tests:
- copy-shortest[12]: the last audio frame is now gone. This is
  correct, since it actually outlasts the last video frame.
- shortest-sub: the video packets following the last subtitle packet are
  now gone. This is also correct.

3 years ago

2 Commits (d80f3debe29821ea1fea2a62aff378695214c1c9)