Macroblocks only at the first seconds of the video

[fernandovg]

Hi. I did some conversions of MP4 video file (AVC) to AVI (XVID, unrestricted profile, wide search, 250 interval between keyframes, 4 b-frames, enable GMC, enable use multi-threads) and every converted video the first seconds of the video is full of macroblocks and after a few seconds (when the frame/image changes completely) the video shows normally until the end.
Here goes the sample of video: http://www.sendspace.com/file/kjflqf (only 1.3MB - the first 5 seconds)

Can anyone help me to understand why this happens and how to fix it?
I'm using FormatFactory (accepts cmd line and its integrated to a program i develop)

[poisondeathray]

Sample of the output video isn't helpful - it would just show macroblocks as you've described.

Sample of the source is more helpful - We are assuming the source is clean

Macroblocks occur because the allocated bitrate isn't sufficient for that particluar section or sample or type of content . So how much bitrate or what quantizer did you use?

You can try bitrate or quantizer override using zones (i.e. allocate a higher bitrate to the begining section)

You can read about xvid zones here:
http://www.divx-digest.com/articles/xvid_setup_page3.html
http://www.gromkov.com/faq/conversion/xvid_options.html (section 11)

[poisondeathray]

I take it back. The sample was useful. You failed to mention "grey" screen. It wasn't just typical macroblocking

This is a decoding error, not low bitrate issue or encoding issue

This can happen if you are using outdated decoder, and the source video doesn't start with an IDR frame. E.g. maybe the version of format factory you are using has a bad decoder, try a different one or use a different decoder

[fernandovg]

Thanks! I'll try and let you know.

[fernandovg]

Do you know any other program that I can convert videos using command prompt ?
I want to do batch video conversion.
thanks

[poisondeathray]

The export goal is xvid/avi ?

You can try ffmpeg, mencoder, xvidencraw

[fernandovg]

I've been trying to use ffmpeg with no success. All converted files have bad, very bad quality.
i'm using -i input.mp4 -vcodec libx264 -acodec copy -threads 2 output.avi

The size of the output file is allways 50% of the original file.
When I use formatfactory the outfile file is more or less 50% larger (I dont fix the size, just want high quality)

As I play my file on the Wii using WiiMC - Wii Media Center - the Wii hardware cant play files with AVC codec. So I just convert mp4 files to AVI files (high quality).
Is there a way to get the same result using ffmpeg?
thanks

[poisondeathray]

-vcodec libxvid for xvid (libx264 is for h.264/avc) . libxvid will give you lower quality/compression than libx264 but if Wii can't play it you have no choice

search for xvid ffmpeg encoding guides. Use a lower quantizer for larger size/quality ; I think it's -qscale in some ffmpeg builds (e.g -qscale 2) , use -help to check the commands

http://ffmpeg.org/faq.html#How-do-I-encode-Xvid-or-DivX-video-with-ffmpeg_003f

[fernandovg]

I tried "ffmpeg -i input.mp4 -vcodec libxvid -qscale 4 -acodec copy output.avi"

the size went to 376MB (original was 327).
When I tried to play a avi chunk message appeared: This AVI file was not prepared for sequential reading, the alternative 'AVI Splitter' will now let the default one handle it.
The avi quality seems much better BUT the video is playing at "high speed". do you know why this high speed and the avi chunk message happened?
thanks again

[poisondeathray]

Not sure; maybe try another ffmpeg binary?

Try one of these
http://ffmpeg.zeranoe.com/

Or you can try xvidencraw.exe - it's the command line version of xvid (xvid vfw is the "official" xvid, but no CLI)