[mythtv-users] 0.24 mytharchive DVD creation issue using SP profile

faginbagin mythtv at hbuus.com
Fri Apr 22 21:41:52 UTC 2011

Hi James,

> Hi. I have a problem creating DVD images using mytharchive. This refers to
> a mythbuntu 10.04.2 system on which mythtv has been updated to 0.24 (from
> repositories, not compiled locally). For what it's worth, the system is a
> combined FE/BE, dual-core, with 3 GB RAM.
> The issue is as follows. When I create the DVD image, if I use the SP
> profile, the resulting iso contains only the first 22 minutes of the
> recording (in the case where the problem became evident, the recording was
> 1 hour and 30 minutes total). The resulting iso ends up being close to 900
> MB in size. If, however, I use the LP profile when creating the iso, the
> resulting image contains the entire recording of 1 hour 30 minutes, and
> not just the first 22 minutes, as happens when I use the SP profile. So
> the problem I'm seeing in creating DVD images seems limited to the SP
> profile.
> My guess is that there is some error coded into the SP profile that
> results in only the first VOB being included in the final DVD image. But I
> don't have sufficient understanding to go beyond this supposition. If I
> did, I'd try examining some configuration or script, looking for errors
> that might cause this profile to exclude all but the first VOB from the
> final DVD image. But I don't even know where to look or what to look for
> in the relevant location. I'm sure, however, that there are those on this
> list who could, if my supposition seems plausible, either instruct me on
> what file(s) to examine and/or what to look for in it/them.
> So, can anyone here respond as to whether my diagnosis of the problem,
> namely that when using the SP profile only the first VOB seems to make it
> into the resulting image, sounds like a plausible one? Further, can anyone
> here instruct me on how to further examine, and possibly fix, the issue?
> Thanks,
> James

I think I can help. I held off answering because I'm currently running 0.23.1+fixes. If there haven't been substantial changes to mytharchive, then my info should apply. But if what I describe doesn't match your environment, then you'll know my knowledge is obsolete.

1) Have you configured a temporary directory for mytharchive to use and verified there's enough space on the partition containing the temporary directory? If not, that might be your problem. I'll refer to it as <mytharchivetmp> below. This temporary file system needs at least 2 times the size of a DVD or 4.38*2 = 8.76 GiB free space - the space used by <mytharchivetmp>, if you want to create a full capacity DVD. and since you're creating an iso file, which is probably in the same file system, you should increase that number to 4.38*3 = 13.14.

2) Have you looked at the log files mytharchive creates when you use it? They are in <mytharchivetmp>/logs. There should be two files, mythburn.log and progress.log. mythburn.log should have the most info. A lot of the info might be cryptic, but maybe an error message will jump out at you.

3) The second from the last step that mytharchive executes, is to create a dvd directory structure using the program, dvdauthor. That directory structure can be found in <mytharchivetmp>/work/dvd. If you look at the subdirectory, VIDEO_TS, you'll be able to check the sizes of the .VOB files that are used to create the iso image. For example, the files that make up the first title on a DVD will be named:
For a 90 minute title using the SP profile, those files' sizes should add up to approximately 3430425600 bytes. I came up with that number using the bit rates specified in the SP profile, which calls for 4771 Kbps for video and 192 Kbps for audio. That equals 4963 Kbps = 5082112 bits/second = 635264 bytes/sec, which means 90 minutes should work out to about 635264 * 60 secs * 90 mins = 3430425600 bytes. The file sizes won't be identical to that number because of factors like variable bit rate and over head for packet headers.

4) The iso image that you've been looking at is created from <mytharchivetmp>/work/dvd. They should have the same directory structure and identical files. You can compare the two my mounting the iso file using the loopback device. The following commands, done as root, should do the trick:
# mkdir -p /mnt/iso
# mount -t auto -o loop <iso-file-name> /mnt/iso
Now, /mnt/iso should look the same as <mytharchivetmp>/work/dvd, except for file ownership and permissions. When you're done examining /mnt/iso, don't forget to unmount it before trying to remove or change the iso file in any way, like re-running mytharchive. The command to unmount is:
# umount /mnt/iso

5) I find VLC media player a useful tool for examining both DVD file systems like <mytharchivetmp>/work/dvd and ISO images, as well as physical DVDs, and a variety of medial files. It shows how long any title on a DVD should be as well as allows you to easily seek to any point in a DVD to conform the title is complete, not to mention providing info on what video and audio streams the title contains, what codecs they use, etc.
If the files in <mytharchivetmp>/work/dvd look wrong and your temporary file system has enough space, there are some other things you can try like disabling the use of FIFOs, re-running mytharchive and then and examining the files created for the title in <mytharchivetmp>/work/1. But you will need another DVD's worth of free disk space to do that.

Hopefully, the above will allow you to in track down, and fix, the root cause of your problem. If not, post back with what you do find, and I'll try to help.


More information about the mythtv-users mailing list