Re: [Mlt-devel] Frame in melt generated mov files missing audio

[Dan D. <da...@de...>]

On Thu, Sep 9, 2010 at 4:30 PM, Kevin MacPhail <kma...@gm...> wrote:
> Hi folks,
>
> I'm trying to use the melt binary included with the mlt package for Fedora
> 13 64bit (MLT mlt-melt 0.5.4) to compile a single mov file from several
> smaller mov files created with ffmpeg.  The compiled mov file looks and
> sounds perfect except the last frame contributed from each of the smaller
> files is missing audio.
>
> This might be overkill, but I wrote a little batch script that generates a
> file named missing_audio.mov (and a few intermediate files) that reproduces
> the problem.  Even if you don't run it it should explain my process.

I reproduced this in a way that I can see exactly what you mean (my
technique requires git beyond last release). I also figured out why.
There is a piece of code in the avformat producer that checks to see
if there are enough decoded/retrieved samples (normally after having
decoded enough) for the requested number, and returns silence
otherwise. On the last frame, I get 1317 samples available but 1333
requested, and those valid samples are not returned by silence
instead.

> #!/bin/bash
> for file in `seq -f test.%04g.png 1 24`;
> do
>         convert -size 960x540 xc:red $file;
> done
> sox "|sox -n -p synth 1 sine 180" test.wav
> ffmpeg -y -r 24 -b 4000K -i test.%04d.png -i test.wav -acodec pcm_s16le
> test.mov
> printf "description=VGA
> FILM\nframe_rate_num=24\nframe_rate_den=1\nwidth=960\nheight=540\nprogressive=1\nsample_aspect_num=1\nsample_aspect_den=1\ndisplay_aspect_num=16\ndisplay_aspect_den=9\n"
>> test.profile
> mlt-melt test.mov -consumer avformat:missing_audio.mov profile=test.profile
> b=40000000 r=24 threads=3 ab=128k acodec=pcm_s16le
>
> Your suggestions and advice are appreciated.

I have to make a bug fix, but 0.5.8 is being released Sunday, and it
is required by the new kdenlive scheduled for Monday. Therefore,
rpmfusion.org should get it fairly soon.

-- 
+-DRD-+