TrueHD AC3 core passthrough

[moviemaniac]

Hi guys,

I've got a bit of a compiling-marathon behind me today having built the latest (fresh from svn) ffmpeg, x264, mplayer, smplayer and VLC (VLC 1.1.0 nightly from 5/2/10 as it was the latest one available that would compile). I got everything to work just as I wanted but one thing gives me headaches as it doesn't seem to work: When I play a Blu-Ray I want VLC to send the core AC3 stream of TrueHD streams to my receiver. This should work - at least according to the changelogs it should work as of 1.0.0) but it doesn't. VLC doesn't recognise the "trhd" stream. DTS-HD works just fine. Do you have any idea how to get support for this? Did I miss an option when configuring ffmpeg or VLC for compilation? Any help would be appreciated.

//edit: Just in case someone's asking: Yes, the new ffmpeg works as it should because I got rid of old libraries and newer stuff and new stuff like PGS subtitles work in the new vlc version I built today.
//edit2: Just double-checked: TrueHD-support has been enabled when building ffmpeg - it gets listed in the enabled audio decoders, muxers and demuxers :

Code: Select all

klaus@klaus-imac:~/Desktop/ffmpeg$ ./configure --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-pthreads --enable-libfaac --enable-libfaad --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libx264 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avfilter-lavf --enable-libdc1394 --enable-libdirac --enable-libschroedinger --enable-libvorbis --enable-libgsm --enable-pic --enable-shared --prefix=/usr | grep truehd truehd vmnc ws_snd1 ea nuv truehd h261 pcm_alaw truehd

//edit3: MLP/TrueHD parser is listed in VLC's "plugins and extensions" list.

PS: A week ago or so I wrote about using the debian multimedia repo - I got rid of these packages _completely_ just in case anybody suggests these being the culprit.

[xtophe]

So what is the actual message about "trhd" in vlc logs?

[moviemaniac]

Okay, I just noticed an error on my part. Previously (with an older version of ffmpeg but one that already supported trueHD I would get an error about TrueHD not being able to get decoded. When I didn't get any trueHD sound with the new ffmpeg build I assumed I had the same error - huge mistake. After your request I just wanted to get you the logs but saw that TrueHD was being decoded just fine. The error was I disabled the internal sound and only had my external A/V-receiver on - the system decoded the TrueHD stream and played it on my computer's speakers - which were muted so I didn't hear any sound, assumed the situation was still the same and posted here...
Still, one big problem remains, but it is nor more of a wishlist-bug: Enabling passthrough of AC3-coreaudio via S/PDIF to an external amplifier because it sucks having to watch 5.1 movies with the crappy internal stereo speakers (sending it to the receiver as PCM stereo via reencoding by pulseaudio doesn't improve things much, either). It already wirks with DTS-HD streams so I hope it's possible with TrueHD too.

[Jean-Baptiste Kempf]

I am not sure you can get the AC3 core from TrueHD in VLC without reencoding....

[moviemaniac]

It can be done. The standard calls for an additional AC3 stream to be offered when TrueHD is being used - I just looked it up, and I made a mistake - it's not a core as in DTS but apparently an independent track. So one way or another, ther IS an AC3 stream already present which *can* be extracted. Programs like tsMuxeR (http://www.smlabs.net/tsmuxer_en.html) offer this very function when ripping Blu-Rays or remuxing m2ts and when looking at the performance and speed as well as the progress indicators I highly doubt any reencoding takes place.

And then there's eac3to - which advertises the exact function of extracting ac3 from TrueHD streams: http://forum.doom9.org/showthread.php?t=125966 Unfortunately it's not a free piece of software