Mpeg4 Modifier

[newnews]

Hi:

I use MPEG4 Modifier to check my avi files that I want to play on DVP642. I got errors for some files, they are:

1. This is not a valid MPEG-4 video(Startcode not found at beginning of frame

2. No VOL found before first VOP

What does this mean? and how to edit this kind avi file without affect video/audio quality so that it can be opened by MPEG4 Modifier?

Thanks

Newnews

[bunyip]

It usually means the Video is not MSMPEG4 or DIVX or XVID, you can use something like AVIcodec to determine what it is, but you'll need to re-encode it to one of the above types. You can use a tool like VirtualDub to do this.

[newnews]

Thanks a lot, How to use VirtualDub to solve this particular problem? I read some article about virtualDub here but I am still confuse for my problem. Could you please explain how to configure the settings when I re-encode the file so as to maintain the audio/video quality as before.

newnews

[bunyip]

It's not really a problem, just a matter of conversion to the correct format, this is what this self-help site is all about.

You will probably have to experiment a bit to get the same quality since different codecs require different settings.

Start by choosing the same bit rate as the source, often though you can get the same quality using a lower bit rate when converting to DIVX or XVID. For Audio choose MP3 and 44100hz. (It would be useful to know what the source details are).

Instructions on how to use VirtualDub are here -> https://www.videohelp.com/avi2divx.htm

Give it a try.

[newnews]

Use AVICodec to check the source, they are already Divx3 or 5 encoded, anyway I use virtualdub to re-encode the files, and seems ok. Now I have another question on one of my AVI file. When I play it in my PC, it has no problem at all, but when I play it in DVP642, The audio have some problem(sometimes it paused for 1-2 seconds, this caused audio video sync problem).
The codec for this file is:
Video : 592 MB, 866 Kbps, 23.976 fps, 640*272 (2.21:1), DIV3 = DivX v3 MPEG-4 (Low-Motion)
Audio : 103 MB, 150 Kbps, 48000 Hz, 2 channels, 0x55 = MPEG Layer-3
what do you think that?

[newnews]

This has solution. VirtuaiDub reported that this avi file has improper audio VBR and suggested to re-encode audio stream. So,
1. save audio stream as wav
2. Choose "direct stream copy" for video and compression from wav file and save as new avi file
I use MP3 qulity 48000Hz, 160kps CBR to compress the wav file. After completion I found that the audio and video lost sync. and then I use MP3 48000Hz, 128kps CBR and LAME MP3 48000Hz, 148kps ABR to compress, same problem happened. I found that the video bitrate was changed to 863kps(Original is 866). When I use 20kbps, 8000Hz, no such problem and video bitrate keep same as original. Why the bitrate for video can be changed? Any suggestion?

[catdaddio6]

i'm curious about the same thing,,except after i converted audio to cbr it was way way outta sync,,so i did a mux of audio from original file into encoded avi,,,it was in sync on pc,but after burning it was outta sync on my 642,,,i tried the menu button thing and ff neither worked,,any idea why