[mythtv-users] transcoding hdtv video to mpeg4 Keeping ac3 5.1

[Matt Mossholder]

On Sat, 2007-05-12 at 18:04 -0700, James Blake wrote:
> Hi,
> 
> I am trying to transcode my 1080i hdtv content to
> mpeg4, it compresses great: Here are the transcode
> settings that I am using:
> _ lossless transcoding
> x Resize video while transcoding
> Width: 960 Height: 544
> Codec Mpeg-4
> bitrate: 2400, max qual: 2 min qual: 15, max qual b/t
> frames: 3
> _ scale bitrate for framesize
> x enable high-quality encoding
> x enable 4mv encoding
> x enable interlaced DCT encoding
> x enable interlaced motion estimator
> Code: Uncompressed
> sampling rate: 48000
> volume 90%
> 
> but when trying to playback the ac3 audio appears to
> be missing.
> 
> when playing with mplayer, forcing ac3 audio, I get
> this:
> Forced audio codec: hwac3
> Cannot find codec for audio format 0x1.
> Read DOCS/HTML/en/codecs.html!
> Audio: no sound
> Starting playback.
> 
> Before, transcode, it definitely had the ac3 sound..
> 
> Is there a way to keep the ac3 audio track????
> 
> I have tried it a couple ways, but it appears to lose
> it no matter what. I need to have my 5.1 surround
> sound.
> 
> Thanks in advance!!!!!
> Jamie
> 

Jamie,
	If you are using an MP4 container (file extension is .mp4), then you
won't be able to store AC3 audio in the file in a way that most players
will understand. The MP4 container format currently only supports MPEG
standards for audio and video, as well as PCM. So you will need to
either do MPEG2,3 or 4 audio to remain in spec for that container
format. 

	If you are using AVI, MKV or any of the others, then I have no idea, I
would think it would work :)


		--Matt