How can I fix wrong AC3s?

[shibby44]

Hi everyone,

I have some movies with problems on their AC3 audios.

Whenever I try to watch them, the player won't start playing them. But if I move the seek bar, to 1sec or less the movie plays perfectly.

From what I read in another posts I guessed it should be a CRC problem so I demuxed the audio and encoded it using BeSweet. Unfortunately the audio got desynchronized. I read somewhere that BeSweet fills the wrong parts of the audio with silences while doing the conversion, so in my case should be filling some ms at the beginning. Maybe I didn't checked the right options to do this, so I leave here the line I used.

BeSweet -core( -input "C:\Tests\wrongAudio.ac3" -output "C:\Tests\correctAudio.ac3" -logfilea "C:\Program Files\GordianKnot\BeSweet\BeSweet.log" ) -azid ( --maximize) -ac3enc( -b 384 -6ch )

The source file was 384kbps 5.1 channel AC3.

Let's hope somebody has an answer for this. Thanks in advance.

Bye.

[unskinnyboy]

Did you try running the original AC3 through AC3Fix (http://www.videohelp.com/tools/AC3Fix)?

[shibby44]

Hi, thanks for your answer.

I tried ac3fix and got the following:

Starting. Input file is test.ac3, output file is output.ac3
Frame length is 1536
Checking frame 198785: OK
Finished. No bad frames encountered

So, the file seems to be ok but still it gets desynchronized when I mux it back in the avi file. The sound comes earlier than it should.

Did I mention that I used VirtualDubMod to demux the ac3 file? Here I found another strange thing. When I look at the streams the original one was 1:46:03.464. The just demuxed file however lasts 1:46:01.056 according to VirtualDubMod. Could it be that VirtualDub removes the first and "supposedly" wrong frames during the demux proccess? if so, which other program can I use so that the file is not processed?

Thank you.
Bye.

[setarip_old]

@shibby44

Hi!I have some movies with problems on their AC3 audios. Whenever I try to watch them, the player won't start playing them.1) Are you saying that neither the video nor the audio starts (unless you move ahead one second), or that the video starts without audio (unless you move ahead one second)?

2) What is the format of the videos (.AVI, .MKV, etc.)?

3) What software and procedures did you use to create the videos?

4) Load one of the problematic videos into GSpot and post a screen capture back here

[shibby44]

Thanks again,

I found some information while doing some tests with Besweet. I tried demuxing the ac3 file with Besweet and got the following. It's a shortened version because the output was huge.

BeSweet v1.5b30 by DSPguru.
--------------------------
Using VOBInput.dll v1.3 by DVD2SVCD (http://www.dvd2svcd.org)
Using hip.dll v1.19 by Myers Carpenter <myers@users.sf.net>
Using Ogg Vorbis v1.0 dlls (http://www.vorbis.com).
Using azid.dll v1.9 (b922) by Midas (midas@egon.gyaloglo.hu).
Using AC3enc.dll v0.1 by Gerard Lantau & Dg (http://ffmpeg.org).

Logging start : 04/19/08 , 16:21:17.

C:\Program files\GordianKnot\BeSweet\BeSweet.exe -core( -input G:\Films\Test.avi -output G:\Films\Test.ac3 -logfilea C:\Program files\GordianKnot\BeSweet\BeSweet.log ) -ac3enc( -b 384 -6ch )

[00:00:00:000] +------- BeSweet -----
[00:00:00:000] | Input : G:\Films\Test.avi
[00:00:00:000] | Output: G:\Films\Test.ac3
[00:00:00:000] | Floating-Point Process: No
[00:00:00:000] | A/V Delay found : 0msec
[00:00:00:000] +-------- AZID -------
[00:00:00:000] | Input Channels Mode: 1+1, Bitrate: 32kbps
[00:00:00:000] | Output Stereo mode: Dolby surround compatible
[00:00:00:000] | Total Gain: 0.000dB, Compression: None
[00:00:00:000] | LFE levels: To LR -INF, To LFE 0.0dB
[00:00:00:000] | Center mix level: BSI
[00:00:00:000] | Surround mix level: BSI
[00:00:00:000] | Dialog normalization: No
[00:00:00:000] | Rear channels filtering: No
[00:00:00:000] | Source Sample-Rate: 48.0KHz
[00:00:00:000] +------- AC3ENC ------
[00:00:00:000] | Bitrate method : CBR
[00:00:00:000] | AC3 bitrate : 384
[00:00:00:000] | Channels Mode : 5.1
[00:00:00:000] | Error Protection: Yes
[00:00:00:000] +---------------------

[00:00:00.000] E7: CRC error // Repeated several times
[00:00:21:088] Stream error : Sync found after 221 bytes
[00:00:00.032] E7: CRC error // Repeated several times
[00:01:16:990] Stream error : Sync found after 84 bytes
[00:00:00.064] E7: CRC error // Repeated several times
[00:04:25:668] Stream error : Sync found after 221 bytes
[00:00:00.096] E7: CRC error // Repeated several times
[00:04:36:650] Stream error : Sync found after 93 bytes
[00:07:57:393] Stream error : Sync found after 133 bytes
[00:00:00.160] E7: CRC error

....
....
....

[00:00:02.656] E7: CRC error
[00:00:02.656] E7: CRC error
[00:00:02.656] E7: CRC error
[00:00:02.656] E7: CRC error
[00:00:02.656] E7: CRC error
[00:00:02.656] E7: CRC error
[00:00:02.656] E7: CRC error
[00:00:02.656] E7: CRC error
[00:00:02.656] E7: CRC error
[00:00:02.656] E7: CRC error
[01:46:19:574] Conversion Completed !
[01:46:19:574] Actual Avg. Bitrate : 0kbps
[00:01:06:000] <-- Transcoding Duration

Logging ends : 04/19/08 , 16:22:23.

After doing this conversion I get a tiny ac3 of some kbs.

setarip_old,
- Neither the video nor the audio start unless I move ahead one second or so. Also I want to mention that the video plays perfectly when I remove the audio from the container.
- The video is an AVI file coded with XviD.
- I don't know it's making procedure because I got it from a P2P network.

Thanks for your answers. Bye.

[setarip_old]

- I don't know it's making procedure because I got it from a P2P network.You might want to RE-read the "Announcement" at the top of the "Newbies" sub-forum, as well as all of the Forum Rules (particularly #6) - especially since any member providing assistance here might also be "struck"...

[shibby44]

It's not copyrighted material if you are referring to that. It's a free to share documentary.

I see there's no presumption of innocence here. Ok, I'll try to fix it by myself.

Bye.