[FFmpeg-devel] eval lavfi filter

[Víctor Paesa]

Hi,
Michael Niedermayer said:
> On Wed, Feb 25, 2009 at 09:07:57AM +0100, V?ctor Paesa wrote:
>> Hi,
>>
>> Michael Niedermayer said:
>> > On Tue, Feb 24, 2009 at 11:56:54PM +0100, Stefano Sabatini wrote:
>> >> On date Tuesday 2009-02-24 23:26:23 +0100, Michael Niedermayer
>> encoded:
>> >> > On Tue, Feb 24, 2009 at 10:39:22PM +0100, Stefano Sabatini wrote:
>> >> > > Hi.
>> >> > >
>> >> > > On date Tuesday 2009-01-20 09:37:21 +0100, V?ctor Paesa
>> encoded:
>> >> > > > There is also a problem for filters that remove frames, as
>> >> ffmpeg uses/expects the fps of the input video (instead of the
>> filtered one) and generates duplicated frames to reach that.
>> >> >
>> >> > ffmpeg should not duplicate frames anymore if the container can
>> >> handle it
>> >>
>> >> Could someone give some more hints about this?
>> >
>> > just try the example that caused frame duplication and check the
>> resulting file, avi/mov/mp4/nut should have no duplicate frames
>> anymore. feedback and bugreports welcome ...
>> >
>> >
>> >>
>> >> Also I suppose this is not necessarily a lavfi-related issue,
>> right?
>> >
>> > no
>>
>> Right, I was able to trace it (but not able to fix) to ffmpeg.c, it
>> seems that do_video() is duplicating frames. Maybe adding a new
>> "-vsync 3" that would not perfom any frame rate duplication?
>
> just tried
> ffmpeg -v 9 -i matrixbench_mpeg2.mpg -r 90 test.avi
>
> no duplicated frames are generated and considering you provide not a
> single word of a hint of what you did or what did not work i cant help

I'm sorry, I answered without reading your commit 17555, please discard
my comments.

Some tests on r17555:

in.avi = http://samples.mplayerhq.hu/avi/fpstest/gwl-bounce-sample-25fps.avi
that is 60 seconds long and has 1500 frames.

$ ffmpeg  -i in.avi -vfilters fps=1 -y -an out_fps1.avi
FFmpeg version SVN-r17555, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --enable-shared --disable-static --cpu=prescott
--extra-cflags=-DX_DISPLAY_MISSING -I/usr/local/include -include
llrint.h --extra-ldflags=-L/usr/local/lib --extra-libs=-l llrint
--enable-gpl --enable-nonfree --enable-libamr-nb --enable-libamr-wb
--enable-swscale --enable-avfilter --enable-avfilter-lavf
--enable-pthreads --enable-avisynth --enable-bzlib --enable-libfaac
--enable-libgsm --enable-libmp3lame --enable-libtheora --enable-libx264
--enable-zlib --build-suffix=-SVN
  libavutil     49.15. 0 / 49.15. 0
  libavcodec    52.18. 0 / 52.18. 0
  libavformat   52.29. 2 / 52.29. 2
  libavdevice   52. 1. 0 / 52. 1. 0
  libavfilter    0. 4. 0 /  0. 4. 0
  libswscale     0. 7. 1 /  0. 7. 1
  built on Feb 25 2009 11:41:58, gcc: 4.2.4

Seems stream 0 codec frame rate differs from container frame rate:
30000.00 (30000/1) -> 25.00 (25/1)
Input #0, avi, from 'in.avi':
  Duration: 00:01:00.03, start: 0.000000, bitrate: 822 kb/s
    Stream #0.0: Video: mpeg4, yuv420p, 640x352 [PAR 1:1 DAR 20:11], 25
tbr, 25 tbn, 30k tbc
    Stream #0.1: Audio: mp3, 22050 Hz, stereo, s16, 56 kb/s
Output #0, avi, to 'out_fps1.avi':
    Stream #0.0: Video: mpeg4, yuv420p, 640x352 [PAR 1:1 DAR 20:11],
q=2-31, 200 kb/s, 90k tbn, 25 tbc
Stream mapping:
  Stream #0.0 -> #0.0
Press [q] to stop encoding
frame=   60 fps= 35 q=6.9 Lsize=     292kB time=59.04 bitrate=  40.5kbits/s
video:252kB audio:0kB global headers:0kB muxing overhead 16.000823%


The out_fps1.avi has 60 frames, as expected, but VirtualDub believes has
1476 frames due to the 25 tbc probably. GSpot reports 60 frames.
ffmpeg is also confused and ffmpeg -i out_fps1.avi out%04d.png produces
1475 PNGs.


ffmpeg  -i in.avi -vfilters fps=1 -r 1  -y -an out_fps1_r1.avi

The out_fps1_r1.avi has 60 frames, works fine in VirtualDub, GSpot, ffmpeg.

Regards,
V?ctor