[FFmpeg-devel] [PATCH v5 24/25] fftools/ffmpeg: Introduce subtitle filtering and new frame-based subtitle encoding

[Michael Niedermayer]

On Sat, Jun 25, 2022 at 09:57:56AM +0000, softworkz wrote:
> From: softworkz <softworkz at hotmail.com>
> 
> This commit actually enables subtitle filtering in ffmpeg by
> sending and receiving subtitle frames to and from a filtergraph.
> 
> The heartbeat functionality from the previous sub2video implementation
> is removed and now provided by the 'subfeed' filter.
> The other part of sub2video functionality is retained by
> auto-insertion of the new graphicsub2video filter.
> 
> Justification for changed test refs:
> 
> - sub2video
>   The previous results were incorrect. The command line for this test
>   specifies -r 5 (5 frames per second), which is now fulfilled by the
>   additional frames in the reference output.
>   Example: The first subtitle time is 499000, the second is 15355000,
>   which means 0.5s and 15.35s with a difference of 14.85s.
>   15s * 5fps = 75 frames and that's now the exact number of video
>   frames between these two subtitle events.
> 
> - sub2video_basic
>   The previous results had some incorrect output because multiple
>   frames had the same dts
>   The non-empty content frames are visually identical, the different
>   CRC is due to the different blending algorithm that is being used.
> 
> - sub2video_time_limited
>   Subtitle frames are emitted to the filter graphs at a 5 fps rate
>   by default. The time limit for this test is 15s * 5fps = 75 frames
>   which matches the count in the new ref.
> 
> - sub-dvb
>   Running ffprobe -show_frames on the source file shows that there
>   are 7 subtitle frames with 0 rects in the source at the start
>   and 2 at the end. This translates to the 14 and 4 additional
>   entries in the new test results.
> 
> - filter-overlay-dvdsub-2397
>   Overlay results have slightly different CRCs due to different
>   blending implementation
> 
> - sub-scc
>   The first entry is no longer in the output because it is before
>   the actual start time and the strim filter removes such entries
>   now (like for video and audio)
> 
> Signed-off-by: softworkz <softworkz at hotmail.com>
> ---
>  fftools/ffmpeg.c                          |  613 +++++-----
>  fftools/ffmpeg.h                          |   17 +-
>  fftools/ffmpeg_filter.c                   |  270 +++--
>  fftools/ffmpeg_hw.c                       |    2 +-
>  fftools/ffmpeg_opt.c                      |   28 +-
>  tests/ref/fate/filter-overlay-dvdsub-2397 |  182 +--
>  tests/ref/fate/sub-dvb                    |  162 +--
>  tests/ref/fate/sub-scc                    |    1 -
>  tests/ref/fate/sub2video                  | 1091 +++++++++++++++++-
>  tests/ref/fate/sub2video_basic            | 1238 +++++++++++++++++++--
>  tests/ref/fate/sub2video_time_limited     |   78 +-
>  11 files changed, 3010 insertions(+), 672 deletions(-)

seems to break fate

Input #0, ass, from 'fate-suite//sub/1ededcbd7b.ass':
  Duration: N/A, bitrate: N/A
  Stream #0:0: Subtitle: ass
Codec AVOption threads (set the number of threads) specified for input file #0 (fate-suite//sub/1ededcbd7b.ass) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some decoder which was not actually used for any stream.
Codec AVOption thread_type (select multithreading type) specified for input file #0 (fate-suite//sub/1ededcbd7b.ass) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some decoder which was not actually used for any stream.
Stream mapping:
  Stream #0:0 -> #0:0 (ass (ssa) -> ass (ssa))
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless if it occurs once at the start per stream)
subtitle input filter: decoding size 1280x720
[out_0_0 @ 0x557cab64bbc0] Subtitle format change from 1 to 3
Assertion c > 0 failed at libavutil/mathematics.c:61
Aborted (core dumped)
tests/Makefile:304: recipe for target 'fate-sub-ass-to-ass-transcode' failed
make: *** [fate-sub-ass-to-ass-transcode] Error 134

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The day soldiers stop bringing you their problems is the day you have stopped 
leading them. They have either lost confidence that you can help or concluded 
you do not care. Either case is a failure of leadership. - Colin Powell
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