TIP Check media files for errors

From Gentoo Linux Wiki

[edit] Introduction

This tip will tell you how to check media files (movies, songs...) for errors.

[edit] Movies

We will use MPlayer for checking movies:

# emerge -av mplayer

If you want to analyze both the video and the audio streams of a certain movie, you can issue the following command:

$ mplayer -vo null -ao null -speed <speed> <file>

Set <speed> value depending on how fast your system can decode the movie without slowing down.

When MPlayer finishes, you have to read the output text displayed in the console and look for suspicious errors or warnings.

[edit] Errors list

Here you are some common errors messages you can come across:

Cannot sync MAD frame

a52: error at resampling

[mpeg4 @ 0x85b65e8]frame skip

[mpeg4 @ 0x85b65e8]Error, header damaged or not MPEG4 header

[mpeg4 @ 0x85b65e8]header damaged

Error while decoding frame!

[msmpeg4 @ 0x85b65e8]ac-tex damaged at

[msmpeg4 @ 0x85b65e8]
error while decoding block:

[msmpeg4 @ 0x85b65e8]Error at MB:

[mpeg4 @ 0x85b6948]slice end not reached but screenspace end

[mpeg4 @ 0x85b6948]concealing

[msmpeg4 @ 0x85b6948]dc overflow- block:

The following is not an error message, but just a warning you can safely ignore:

[mpeg4 @ 0x85b65e8]looks like this file was encoded with (divx4/(old)xvid/opendivx) -> forcing low_delay flag

If you are not sure the movie is broken, ask MPlayer's folks in IRC (channel #mplayer, server FreeNode) or through the mailing lists.

[edit] Songs

[edit] MP3

mpck will check mp3 files for us:

# emerge -av mpck

This tool is pretty easy to use. Just:

$ mpck <mp3song>

or

$ mpck *.mp3

I suggest the following options:

• -r: scans directories recursively and checks all files ending in .mp3
• -q: prints only good or bad for each file
• -B: prints statistics only for bad files

[edit] Ogg Vorbis

If you want to check Ogg Vorbis files you can use the ogginfo tool which come to you with vorbis-tools package:

# emerge -av vorbis-tools

This tool is pretty easy to use. Just:

$ ogginfo <oggvorbissong>

or

$ ogginfo *.ogg

I suggest the option -q for printing essential informations only.

[edit] Musepack

Musepack songs can be checked with the mppdec tool from musepack-tools package:

# emerge -av musepack-tools

This tool is pretty easy to use, too. Just:

$ mppdec <musepacksong> /dev/null

or

$ mppdec *.mpc /dev/null

[edit] Links

From Gentoo Forums:

• Checking movie file integrity?
• how can i check for corrupted movies?

From MPLayer users mailing list:

• Integrity check
• feature request...

Others:

• HOWTO: Check avi file for errors