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| MrSmite |
| Posted: Jul 20 2013, 09:44 AM |
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Advanced Member
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Joined: 30-May 09
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I bought a couple tv episodes for web download and noticed that the "previously on" portion of the audio track is 2ch while the main presentation is 5.1 ch.
I assume** that if I try to burn this to DVD, the audio track will be marked as 2ch. since that is what comes first in the stream. Can I transcode the first 90 seconds to 5.1 without cutting the audio stream? I'm concerned if I have to demux, cut, transcode and remux that I'll skew the sync.
Thanks!
** I would be using Sony DVD Architect 4.0 and the only audio option it has is "Audio Format" with three choices: PCM Stereo, AC3 Stereo, AC3 5.1. |
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| malky |
| Posted: Jul 20 2013, 06:39 PM |
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Surely it's 5.1 except that the intro has silence on the surround channels?
What does VirtualDub or MediInfo report about the audio. |
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| MrSmite |
| Posted: Jul 21 2013, 12:30 AM |
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| QUOTE (malky @ Jul 20 2013, 06:39 PM) | Surely it's 5.1 except that the intro has silence on the surround channels?
What does VirtualDub or MediInfo report about the audio. |
Here's a trimmed version of MediaInfo's output:
ID: 2
Format: AC-3
Mode extension: CM (complete main)
Duration: 57mn 26s
Bit rate mode: Constant
Bit rate: 384 Kbps
Channel(s): 2 channels
Channel positions: Front: L R
Default: Yes
Forced: No
Note: There are no other audio streams listed.
What's interesting is when I play the video in MPC-HC using FFDshow, during the "previously on" it shows the input is "AC3 Stereo" but when the main content starts it shows the input is "AC3 5.1". |
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| MrSmite |
| Posted: Jul 23 2013, 07:29 AM |
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Well, after more searching I found that this is a common problem for TV episodes because the intros (and commercials if applicible) are usually in stereo.
Google eventually led me to a thread* on the doom9 forums which linked to a program called SplitAC3. When I ran it I got two files (one 2 ch., one 5.1 ch. ) and this log:
| QUOTE |
FileSize : 158879232 bytes
---------- First valid Header
Time eq. : 3309984 ms.
SamplCod : 0 (0:48, 1:44.1, 2:32 KHz.)
BitRate : 384 Kb/s
ChanMode : 2 (1:1/0, 2:2/0, 3:3/0, 4:2/1, 5:3/1, 6:2/2, 7:3/2)
FrameSize: 1536 bytes
---------- Process ( 23.976000 fps is used for Trim)
Time: 0 ms. Written: 4690 frames 2.0 ( 150080 ms.)
Time: 150080 ms. Written: 98747 frames 5.1 ( 3159904 ms.) Trim(3598, 79359)
---------- End of File
Total time: 3309984 ms. at EOF
T. written: 98747 frames 5.1.
T. written: 4690 frames 2.0.
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So at least I can make a fake 5.1 out of the 2 ch using Vegas and combine that with the main track. Not ideal but considering that my DVD authoring program insisted the whole track was 2 ch., it's better than nothing.
Also, the commandline accepts an FPS value so the 5.1 gets trimmed properly so hopefully I won't knock things out of sync.
*Edit:
The HTTP button on the forums doesn't work for me (firefox 22) so here's the link:
http://forum.doom9.org/showthread.php?p=14...695#post1447695 |
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