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Old 17th November 2008, 16:39   #1  |  Link
tvconfuse
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detecting audio FPS?

I don't know if there is FPS info in an audio stream but I'm just wondering because I'm having sync issues.

I used eac3to to convert a ac3 5.1 640 track to a ac3 2.0 384 track.

I never had a problem in the past but with this track, after the conversion and muxing back video/audio, I find the audio is out of sync with the video.

The original file is fine, and I demuxed the original file with eac3to as well.
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Old 17th November 2008, 16:54   #2  |  Link
madshi
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Audio tracks usually don't have FPS information stored in them. Which kind of movie are we talking about? Blu-Ray? Broadcast? Some broadcasts switch between 5.1 and 2.0. That is problematic and eac3to (and also some DirectShow decoders) can't handle this situation very well. If the original stream is straight 5.1 then the downmixed AC3 track should have the same sync as the original 5.1 track (unless there's a bug in eac3to or in the AC3 de/encoder).
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Old 17th November 2008, 16:55   #3  |  Link
nautilus7
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Did you change/encode the video? If not the new audio should fit.

Do you get any error massage during creating the new audio track?
What is your final format/container? How do you mux audio and video?
What programs do you use to play the video/audio? Maybe it's just a playing back problem only.
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Old 17th November 2008, 17:08   #4  |  Link
tvconfuse
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The Video file was from a blue-ray movie captured using HDPVR.

I didn't change/encode the original file. I still have the original file.

- used Eac3to to demux the original into separate video + audio files (video.h264 & audio.ac3)

- used Eac3to change the audio from Ac3 5.1 640 48000 to an Ac3 2.0 384 48000 track.

- muxed audio and video using tsmuxer back into a .TS file (tried .m2ts as well)

- played the resulting file on my PC using powerdvd 8, sync problems, played on ps3, sync problems

What i did notice was when i demux the audio and video, the audio file looked liked this

"move.ac3 5.1 640 48000 -27db 1888ms"

Not sure if the 1888ms means a delay or not
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Old 17th November 2008, 17:13   #5  |  Link
madshi
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Quote:
Originally Posted by tvconfuse View Post
The Video file was from a blue-ray movie captured using HDPVR.
Why so complicated?

Quote:
Originally Posted by tvconfuse View Post
- used Eac3to to demux the original into separate video + audio files (video.h264 & audio.ac3)

What i did notice was when i demux the audio and video, the audio file looked liked this

"move.ac3 5.1 640 48000 -27db 1888ms"
That is strange. If you demux with eac3to, the audio file normally is automatically delay corrected. So the 1888ms should not have been part of the audio file name. Please post the full eac3to demuxing log here.
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Old 17th November 2008, 18:00   #6  |  Link
tvconfuse
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I used HDPVR to also record HDTV Shows and I don't have a blue

Actually the

"ac3 5.1 640 -27db 48000 1888ms" doesn't show on the resulting file,

it shows that info when I do

eac3to X:\movie.ts

1: movie track info...1080i ...
2: ac3 5.1 640 -27db 48000 1888ms

x:\
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Old 17th November 2008, 22:55   #7  |  Link
madshi
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Ok, I'd suggest these tests:

(1) Let eac3to mux video to MKV. Then use mkvtoolnix to add the audio track into the MKV. Does this play in sync?

(2) Let eac3to demux video and audio. Then use tsMuxeR to mux both unchanged to TS. Does this play in sync?

These tests should finding out where the problem occurs exactly...
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