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Old 12th November 2009, 14:01   #1327  |  Link
JungleBoy
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Since the BBC HD changed their encoders over in August the audio is now transmitted either at 192Kbps 2 channel or 384Kbps 6 channel AC3. When demuxing a TS file with 192Kbps 2 channel audio (with either with DGAVCIndex or DGAVCIndexNV) the ac3 filename is created with 384Kbps 6 channel in the name. Media Info says the ac3 file is 192Kbps 2 channel.

I suspect the BBC HD TS stream is always set to 384Kbps 6 channel to prevent switch over problems which may confuse DGAVCIndexNV. When playing the ac3 file using either VLC v1.0.3 or MPC-HC v1.3.1301.0 (with ffdshow 3078) the duration shown is half the actual duration with a bitrate shown of 384Kbps. The audio sounds ok but the timer shown is wrong.

Muxing the ac3 file into the MKV works and no one would be the wizer. Media Info shows the MKV apparently containing 384Kbps 6 channel AC3 audio when it's really 192Kbps 2 channel AC3. Muxing the ac3 into an AVI causes the audio to be played back at double speed.

I've been using the latest version of Audacity (that supports AC3) to create an ac3 file with 192Kbps 2 channel before muxing with the MKV or AVI. A better way it seems is to put the TS file through tsMuxeR GUI to create M2TS. If the M2TS is put through DGAVCIndexNV the ac3 file comes out at 192Kbps 2 channel with the correct filename as well so no fiddling is needed with Audacity.

Another question.
If the TS file contains continuity errors I assume it's better to create M2TS as I understand it contains timing information.
When demuxing the audio from the TS, compressing the 264 and re-muxing the video and audio into MKV or AVI, lip sync errors can often be seen after a continuity error as occurred especially with AVI files.
Will this lip sync error be prevented/reduced if M2TS is fed into DGAVCIndexNV rather than the raw TS file ?

Last edited by JungleBoy; 12th November 2009 at 14:11.
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