AC3 encoding produces empty file

[DeadLily]

My goal is to burn to DVD a 90 second Quicktime (DV) movie that I exported from FCP3. I’ve been successful at using the mpeg2enc codec to create a working mpg2 version of the file. Only by using VLC can I confirm that the mpg2 file has sound. When I create the file, I have DVD folders created. I use Toast Lite to burn the folders to a DVD-RW. My Mac DVD Player (3.2) acknowledged the DVD-RW, but playing it is “NOT PERMITTED”. My Pioneer DVL-909 plays the DVD-RW fine, but there is no sound on audio track 1. (Audio track 2 plays the mp2 sound. Is there a way to have those switched during encoding?)

So after reading the docs (duh), it points out that mpeg2enc does not create AC3 sound.

I then used ffmpeg (video passthrough) to create an AC3 track from the original DV Quicktime file. However, every attempt to run the process creates an AC3 document with Zero kb. Sometimes there is no encoding at all; I press "Encode", it dings immediately and tells me it's finished.

When I solve that problem, I expect my next difficulties will be in having the mpg2 file and the AC3 file muxed, because when I try it with the existing files, the mux tool declares that the mpg2 file is “unrecognizable”.

I’m using an iMac G3 with 10.2.8 and ffmpegX 0.0.9a.

[major]

I then used ffmpeg (video passthrough) to create an AC3 track from the original DV Quicktime file. However, every attempt to run the process creates an AC3 document with Zero kb. Sometimes there is no encoding at all; I press "Encode", it dings immediately and tells me it's finished.

Enable "Invert mapping" when converting video+audio to audio.

[DeadLily]

"Enable "Invert mapping" when converting video+audio to audio."


Thank you for the reply. I went back and tried that several ways, but the results are the same, the immediate creation of an ac3 document with no data in it.

The sound in my original DV file is of aiff quality, 48000Hz, 16 bits. I realy wish I understood what the problem is.

[major]

Try to select the "Movie audio to mp3" preset then change mp3 codec to AC3.

[DeadLily]

Try to select the "Movie audio to mp3" preset then change mp3 codec to AC3.

Hmm... at least with this procedure, it thinks for a while. It even sounds like it's actually converting something. But the result is still an empty file. If it helps, here's what the info looks like:


printf "Encoding started on " && date && /Applications/ffmpegX.app//Contents/Resources/ffmpeg -i /filmprojects/Dancingproject/Dancing\(DV\).mov -y -vn -f ac3 -acodec ac3 -ab 128 -ar 48000 -ac 2 -map 0.1:0.0 -benchmark /Volumes/Crow/ac3audio.ac3 && printf "Encoding completed on " && date && printf "\a"


Encoding started on Mon Jan 26 22:57:48 PST 2004
Input #0, mov, from '/filmprojects/Dancingproject/Dancing(DV).mov':
Stream #0.0: Audio: pcm_s16be, 48000 Hz, stereo, 1536 kb/s
Stream #0.1: Video: dvvideo, 720x480, 29.97 fps, 800 kb/s
Output #0, ac3, to '/Volumes/Crow/ac3audio.ac3':
Stream #0.0: Audio: ac3, 48000 Hz, stereo, 128 kb/s
Stream mapping:
Stream #0.1 -> #0.0
CODECID 31 31 sowt
bench: utime=133.920s
Encoding completed on Mon Jan 26 23:01:29 PST 2004

[major]

OK, you must export the audio to WAV by using Quicktime Player first.

[DeadLily]

OK, you must export the audio to WAV by using Quicktime Player first.

At least that produced a file with content, however only 116 kb, from a WAV file that’s 17.4 Mb. I ran the process a second time, same conditions, and got another ac3 file that’s 1.4 Mb. Muxing and burning either of these to the m2v file from the original video conversion produced good folders which burned fine. But neither of them would play any sound from my DVD player (which acknowledged the audio track as a Dolby Digital track).

I exported the WAV file from FCP3, since Quicktime 6.4 does not have an export feature. FCP3 would not let me export the a-v sequence with a WAV file, so I exported it with only the audio. Playing the WAV file on Quicktime verified it does have sound.

[major]

If you have FCP3 then you can use A-Pack to generate the AC3 stream.