Missing part of audio

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Missing part of audio

Postby BigGtheDood » Sun Mar 27, 2011 12:43 am

I am converting an AVI file to DVD and a portion of the very end of the film has no captured audio. When playing the AVI file the audio is there. I am using Avi2Dvd and the only audio stream available, AC3 CH2 with the audio bitrate set at default of 384, and I've tried both ECEnc set at Profile: best and Matrix: mpeg and QuEn Use VBR, Hi Quality.
Is there something I'm missing to capture this audio, which is certainly on the AVI video.
BigGtheDood
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Re: Missing part of audio

Postby H.Ammer » Sun Mar 27, 2011 3:51 pm

If your AVI file plays with audio throughout then you have a "captured" audio stream. What I think you are saying is that it was not fully converted during the process to be "muxed" and then "authored" on to a DVD. There are two distinct possible errors, continually or progressively "out of synchronization" or a faulty audio stream that fails during processing and becomes truncated. You will need to check to see if either is the case. Download and install MediaInfo and direct your AVI file to it and obtain a "text" report. Look at the report and see if the audio stream duration matches the video stream, also check to see if there is a video delay (in the audio section) and note the video frame rate. Should the frame rate not be 23.976 fps or 25 fps for either PAL or NTSC or 29.97 fps for NTSC then you can expect audio duration issues resulting from a non-standard frame rate. If your investigation suggests that the audio stream has become truncated during processing then the odds are a faulty audio stream, probably as a result of poor editing of the AVI file. All is not lost as the audio stream can be "demuxed" from the AVI file, repaired including re-commpessing, then re-muxed. As the number of options available are huge, it is necessary to identify the problem to enable a solution. Please copy and paste your text report from MediaInfo (above) into a reply, so a more detailed solution can be given. Also state if you are trying to change the framerate to PAL or NTSC.

The video encoder settings have no direct baring on the audio stream as that stream is split first from the AVI file before the video is processed. Once the audio stream has been split or de-muxed, it is then fixed and converted as required. The video stream is processed next to produce a compliant video only file, before it is added to the processed audio stream and sub-pictures (subtitles) as required to give a very large output MPG file. This file is "authored" to produce a DVD file-set (VIDEO_TS and an empty AUDIO_TS folder), and if you did not un-check "MakeISO" option, then an additional ISO image file. As the available space on a DVD is finite, as in fixed, you should not over specify your audio stream as this will only increase the audio stream file size and so reduce the available space for the video stream, and so reduce the video quality or bitrate. So please set the audio bitrate for a stereo (2.0) audio stream to no more than 192 for mp3 or AC3, or 384 or 448 for 6 channel (5.1) dolby AC3 streams. See the MediaInfo report for details on the original audio bitrate, and set identically for AC3 or the nearest higher bitrate for mp3.

You do not require the ISO image file as the DVD file-set can be burned onto a DVD using most DVD burning software, especially ImgBurn that is recommended, Nero is not. By not making the ISO image file some of the working file will not be overwritten in the temporary folder and can be played to see if these files function correctly, and so help identify where an error occurs.

Please try the above, and post the MediaInfo text report so further help can be offered. If you are successful or not in finding a solution then please advise. This way other people who find themselves with similar problems can make use of your experience.

Good luck, and I look forward to see how you get along.
H.Ammer
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Re: Missing part of audio

Postby BigGtheDood » Sun Mar 27, 2011 6:00 pm

Thanx much for the help. The moment I read your variance in fps between PAL and NTSC I knew immediately what my problem was, that the video was produced in the UK and I had not given thought to the difference in broadcast systems, and running the prog again with the correct params (convert PAL to NTSC) corrected the issue.
BigGtheDood
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Joined: Sat Mar 26, 2011 7:09 pm
Location: Piedmont area North Carolina


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