[MEncoder-users] ac3 mistaken for mp3 in recent versions of MEncoder

[Laine Lee]

On 4/30/10 12:39 PM, "Reimar Döffinger" <Reimar.Doeffinger at gmx.de> wrote:

> MPlayer can't even play it (that kind
> of thing is a really good idea to test btw., it makes the description
> much simpler and we can analyze the issue faster).

That might be more useful for someone more experienced with MPlayer than I.
It's typical for me to be unable to get things to play correctly until
they're encoded.

> It seems FFmpeg does not recognize the file as a valid AC3 file (or
> actually it misdetects it as MP3 - which I guess could be the fault
> of how MPlayer uses it currently).
> As a workaround you can just add
> -audio-demuxer rawaudio -rawaudio format=0x2000
> to your commandline.

That didn't seem to allow me to workaround it. I am able to transcode the
file using a sox pipe that I normally use to adjust duration by applying an
imperceptible tempo change:

ffmpeg -v 0 -i input.ac3 -f sox - | sox -S -V -p -p tempo 1.00005 | ffmpeg
-v 0 -i - -acodec ac3 -ab 448000 -y output.ac3

I took out the tempo adjustment, and the resulting file seemed to allow me
to work around the problem. Ffmpeg seems to handle the ac3 file for that
operation successfully.

If you still have it around, or would care to download it again
(https://rowdyspace.utsa.edu/users/mek985/share/Target/flyClip.zip), would
you make a suggestion about how to ignore some of the video file's
information (high resolution, for example) to allow playback that doesn't
demand as much from the computer?

Do you have any suggestions about how to to decrease blockiness in parts
that have low luminance and contrast? Should I add some noise to just those
parts? How?

Would I need to submit a bug report to ffmpeg-users (or developers) to make
the feature request for built-in capture capability from my device
(Hauppauge HD-PVR) for Mac OS X?

Thanks again. 

Laine Lee