[mythtv-users] MPEG4 transcode - lost subtitles and additional audio tracks

Matt Mossholder matt at mossholder.com
Fri Mar 30 03:04:01 UTC 2007


On Thu, 2007-03-29 at 09:20 +0100, Robin Hill wrote:
>  
> Actually, MPEG-4 is also a container (usually using the .mp4 extension)
> and can contain multiple audio streams.  I don't think these are what
> Myth is using though - there's not much in the way of tools for
> creating/using MPEG-4 containers.
> 
> Cheers,
>         Robin
> 

MP4Box from the GPAC project ( http://gpac.sourceforge.net ) seems to
work nicely. I've found that the problem isn't so much getting files
into .mp4 containers, it is getting the players to make use of all the
features of the container. 

For example, I believe that currently only VLC supports native MPEG-4
timed-text subtiles, which MP4Box converts SRT subtitles into. 

I also haven't found any linux players that support Nero's MPEG-4
chaptering extension, which is also supported by MP4Box.

MP4Box does come with its own player, which supports some of these
features, but I have never managed to get it to work.

Probably the biggest drawback to MPEG-4 containers currently, though, is
lack of support for non-MPEG compliant streams.... no AC3, no DTS, no
alternate video codecs. You can do MPEG 1, 2 or 4 for all your video and
audio, and that is it.

I've been trying to future proof my videos, by going all MP4 containers
with H.264 video and AAC/MP4 6 channel audio, but for now, it is
somewhat painful...

		--Matt




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