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

Reimar Döffinger Reimar.Doeffinger at gmx.de
Sat May 1 16:10:08 CEST 2010

On Fri, Apr 30, 2010 at 04:14:26PM -0500, Laine Lee wrote:
> On 4/30/10 12:39 PM, "Reimar Döffinger" <Reimar.Doeffinger at gmx.de> wrote:
> > 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.

Worked for me. Either way it is fixed now in latest SVN.

> 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?

Yes, but unfortunately most (at least when combined) currently crash, some are "broken" on principle.
-lavdopts threads=2
-lavdopts skiploopfilter=all
-lavdopts lowres=1
Since you seem to be using OSX: try -vo gl. It's not working well with OSX,
but at least it doesn't have the ridiculously bad performance of -vo quartz
or -vo corevideo.

> 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?

That depends on what exactly it is. It might make most sense to adjust brightness/contrast
so these are not visible.
Otherwise there's -vf gradfun or -vf fspp which may or may not help.

> 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?

That belongs to roundup.ffmpeg.org, however I see little chance of anyone implementing
OS-X specific features, most OSX APIs are designed in a way that makes them a pain
to use from a command-line application like MPlayer and FFmpeg and we don't have any
particularly active OS X developers anyway.
If I understood you right, that capture program creates captures in some proprietary
format, getting that support even is more likely that OS X capture support I think.
Of course none of this is an argument against filing a feature request...

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