How to downsample Apple HD Movie Trailers to 2 Channel Audio

[jac1d]

(I have realized this was misposted under general Linux and probably belong here instead, I'm moving it over and will place a link back in the previous area instead.)

EDIT: I am running "VLC media player 0.8.6a Janus" on Debian Etch

Hello All,

First let me say that VLC is a truly amazing piece of software, probably one of the most impressive opensource applications I've ever had the pleasure of using. Thank you to everyone involved and can you please point me in the direction of where to make a donation or a list of things the project maintainers would like contributed.

Now, on to my current challenge:

I am currently doing a lot of work with IPTV multicast streams and I've run in to an odd problem.

I am streaming various HD Movie Trailers from http://www.apple.com across the network using the following string:

#!/bin/bash
vlc -d -vv $1 --sout '#transcode{acodec=mpga,ab=224,channels=2}:standard{access=udp,mux=ts,dst=239.1.0.51,}' --loop

Where $1 is any of various HD trailers I downloaded today.

The first few trailers I tried worked great and had audio on the IP set top box I am using.

Here is one that worked fine:

http://movies.apple.com/movies/paramoun ... h1080p.mov

The clip played with audio either way in the windows VLC player (that is without the transcode line above and after being transcoded), presumably because the player handles >2 channel audio without any issues. However the IP set top handles only 2 channel audio at the moment.

I was pleased with the result so I downloaded a number of additional trailers, but the identical command line options for 2 channel audio transcode resulted in garbled audio on BOTH the windows VLC playback machine as well as the IP set top box. I suspect because the audio encoding format is different and I'm not using the correct options to transcode I'm only guessing.

Here is a clip that does not play properly (when transcoded and streamed with the vlc string above) on either VLC or the IP STB:

http://movies.apple.com/movies/touchsto ... h1080p.mov

I would really appreciate some assistance on how to transcode clips like these to 2 channel MPEG audio. Can anyone offer any advice?

Thanks in advance.

-Jeff

** This looks like it was an open bug (http://trac.videolan.org/vlc/ticket/990) from early last year and may have been fixed, although it is unclear exactly when the fix went in the release tree, it may have been added as recently as January, 2008. Either way, I will upgrade to current stable and see if it is fixed.

[jac1d]

Since I haven't had any success or any replies I thought I would post an update.

I tried compiling VLC stable 0.8.6d from source on Debian Etch. After much fiddling with the rules file to update it for some of the recent changes (the source file in the svn appears to be for 0.8.6a), and adding back in x264 support, I was unable to get the videos (even the ones I had working sucessfully under 0.8.6a) to play at all. No video and no sound.

When that didn't work, I decided to take a test system to debian testing level and did a full apt-get upgrade to testing (lenny), removing my 0.8.6d deb and installing from the testing repo, which gave me 0.8.6c. This also resulted in no video or audio using the exact same command line that works under 0.8.6a on Debian Etch (stable).

I'd appreciate it if I could hear from anyone who is successfully playing/downsampling the Apple HD trailers to 2 channel audio (but 1080p video). I'd also appreciate knowing what OS and VLC versions/libraries you are using to help steer me in the right direction.

Thanks,

-Jeff

PS - This thread looks like it is along the right lines viewtopic.php?f=7&t=44079 regarding the AAC issue.

I guess the next step is to try SVN. I found this post regarding building VLC SVN on Debian Etch viewtopic.php?f=13&t=43930&p=139207

[jac1d]

Ok, a bit of an update. I got the SVN from last night installed. Some of the trailers that had audio problems play properly (but don't loop properly, as far as I can tell), and many others just segfault during the initital attempt to launch the stream.

Given that it is a nightly build I suspect there is active work going on in this area.

I will post more details about what files work and what ones segfault tomorrow, to help people debug.

-Jeff