[FFmpeg-user] Reading directly from .iso DVD image

[Etienne Desautels]

On 2016-01-13, at 11:22, Nicolas George wrote:

> Le duodi 22 nivôse, an CCXXIV, Etienne Desautels a écrit :
>> After more tests I hit some problems with some videos:
>> ffmpeg -hide_banner  -i /mnt/archivescollection/test_file.iso -f null -af ebur128=peak=true:framelog=verbose -vf idet,cropdetect=0.12:2:1 -y /dev/null /mnt/archivescollection/test_file.iso: Invalid data found when processing input
> 
> The ".iso" format is not a multimedia format, it is the octet-per-octet
> image of a ISO 9660 / UDF file system with files in it. Since most of the
> payload is MPEG-PS, a format without global headers and enough resync code,
> reading the file directly will likely find some near the beginning and treat
> the rest of the data as garbage, but that is pure luck.
> 
> If you mount the filesystem, you can observe that the payload is fragmented
> in large-but-not-huge files, and the payload in these file contains program
> and menus together, possibly out of order.
> 
> There is a script in the tools directory that can generate a concat script
> file for a given DVD title, with quite a few limitations. It could be
> extended to work with ISO images from the outside.

Hi Nicolas,

I already know all that, partly thanks to you and I already use dvd2concat. But, as I have written, by accident I passed an .iso file directly to ffmpeg and it works. It was a surprise for me. I didn't did a lot of tests, but I can extract images, convert some parts with seek, etc. I didn't check the time exactitude of those extractions. ffprobe reports the correct complete time of the DVD (as lsdvd). But, for at least one .iso, I have an error that I don't have when mounting the .iso manually.

I have searched ffmpeg's code to check for .iso support but didn't found anything? But I don't know well the ffmpeg's code so my search is not optimal.

I decided to continue to mount .iso manually and using dvd2concat for production.

Regards,

Etienne Desautels