Can this be done?

[baturjan]

I have mpeg2 files from my Panasonic SV-AV100. To avoid quality loss, I use Stream Clip to cut out unwanted scenes, then Toast it to DVD.

The info on the MPEG is:

Muxrate : 10.08 Mbps
Aspect ratio 4/3 (TV)
Interlaced, chroma format: 4:2:0
Size [704 x 480] 29.97 fps 5.74 Mbps
Audio : Mpeg 1 layer 2
256 kbps 48000 Hz
Stereo, No emphasis

What I'm trying to do, but can't, is to edit the audio while maintaining the video/audio sync. Here's what I've tried:

1. demux with either bbDEMUX, BitRateHelper, or MPEG2Works
2. convert mp2 to aiff with either MPEG2Works, Toast, or Amadeus
3. import aiff to Final Cut Express to edit the volume level and add a track or two
4. export audio tracks from FCE to a single aiff file
5. convert aiff to mp2 at 256 bit rate with BitRateHelper because that's the bit rate of the original mp2.
6. Multiplex the new mp2 and the original demuxed m2v

First I thought the out of sync problem was due to converting the edited aiff file to mp2 at a bit rate of 224. So I tried BitRateHelper to convert it at 256, but I still get out of sync problems.

The out-of-sync pregresses through the clip. You don't notice it at the beginning but it gets progressively worse to the end.

No matter what I try, the audio and video never sync. Is it possible to do this without the audio getting out of sync?

[terryj]

1. edit the audio as needed in Amadeus II or Sound studio.
2. save the audio out as AIFf, 16bit , 48khz.
3. open the AIFF in QT Pro.
4. Open the m2v

now of course, I'm just guessing here, but the audio will be slightly off ( even by a few seconds) to the video's length
because of your additions/edits.
so,
5. select all video, copy all video
6. select all audio, add scaled the video to the audio.
7. save out as ( export to) .dv file ( dv NTSC, locked audio).

8. Play resulting file. Is everything like you want?
if so
9. open .dv file in FCP, send to DVDSP to author and burn.

[820am]

Maybe I'm missing something (maybe not), but couldn't you trim out the sections in MPEG Streamclip, preserving the sync? I've done this w/ eyeTV recordings with success.

[alph]

(oops)

[baturjan]

I'm trying to avoid decompressing and recompressing. Otherwise, the video quality takes a major hit. That's why I use MPEG Stream Clip in the first place. It allows my to cut out unwanted sections without decompressing.

However, Stream Clip does NOT allow you to edit the audio (i.e., adjust the volume level, add aditional tracks, etc.). That's why I'm "extracting" the audio only, and edititng it in FCE., all the while leaving the video track "untouched".

If I were to export it to DV, then I would simply do all the editing in FCE and it wouldn't be a problem. However, I'm starting with an MPEG2 and to decompress and recompress the video results in major quality loss.

I'm not "lengthening" or "shortening the audio track, at least I'm not trying to. I'm only adjusting the volume level at certain parts.

[820am]

Well, if you edit the whole thing in Stream Clip, make a new file, then rip the audio from that file, play with it, then put the two (the original, stream clip't video and the amped audio), you ought to sync.

[baturjan]

Well, if you edit the whole thing in Stream Clip, make a new file, then rip the audio from that file, play with it, then put the two (the original, stream clip't video and the amped audio), you ought to sync.

Thanks for the suggestion. Do I understand you right?

My file name is 123.mpeg. So,

1) duplucate 123.mpeg
2) rip the audio from the duplicate
3) edit the ripped audio in Stream Clip?
4) Put the ripped/edited audio together with the original 123.mpeg

I don't want to put the edited audio into the original because that will give me two identical audio tracks. If I drop the volume, it won't be noticed. Also, I'd like to add other audio tracks of music.

HOwever, I did try to simply edit the audio with some fading in Amadeus, and multiplex it back. the premiminary results are promising, though the clip was only 2 minutes. I'm going to test a longer clip to see for sure.

Even if it does work, I don't see in Amadeus how I can control volume easily, nor add additional tracks. It's only a two track application.

[820am]

I thought you needed to edit the file, then amp the volume?

[baturjan]

Yahoo it woks!!!

I think Stream clip did it. I used Stream Clip to demux the mpeg to m2v and aiff.

I edited the aiff audio file in Final Cut Express, then exported it to aiff.

I then used BitRateHelper to convert the aiff to mp2 at the original bit rate of 256.

Then I used BitRateHelper to multiplex the new mp2 audio with the original m2v.

At 7 minutes the audio was right on sync!! I'm stoked!

I think my problem was using MPEG2Works wich only handles bit rates of 224. Nothing against MPEG2Works. I think it's a great app, and getting better.

[sjk]

Maybe you meant BitViceHelper?