<div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Why would mplayer and VLC beable to play the iso file while mythtv's player can't? I was under the impression that ddrescue is able to overcome the errors on the disc.<br>
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On 09/05/2012 12:37 AM, Nick Rout wrote:<br>
> On Wed, Sep 5, 2012 at 3:33 PM, Michael T. Dean wrote:<br>
>> On 09/04/2012 07:40 PM, Michael Herman wrote:<br>
>>> Hi there,<br>
>>><br>
>>> I am new to this mailing list; although I have used Mythtv for quite<br>
>>> awhile (although I still feel like a beginner at it). I recently got a<br>
>>> large enough harddrive that I wanted to put my DVD collection on it as .iso<br>
>>> files. I followed the directions at:<br>
>>> <a href="http://www.cmdln.org/2010/01/22/backing-up-disney-dvds/" target="_blank">http://www.cmdln.org/2010/01/22/backing-up-disney-dvds/</a> to create a .iso<br>
>>> file of Hunger Games. When I play it through the video browser it plays a<br>
>>> bunch of previews at the start of the disk, each of which seems to be a<br>
>>> seperate chapter of the DVD. But after that it just quits and never shows<br>
>>> the Main Menu. If I play it outside of Mythtv with VLC or mplayer it goes<br>
>>> stright to the main menu.<br>
>>><br>
>>> I read that mythtv doesn't support menus but it seemed dated and I<br>
>>> couldn't find info for Mythtv .25 which I am using. Is there anything<br>
>>> obvious that I should try? I could always use an external player but I<br>
>>> wanted to see if mythtv would be fine so I didn't have to mess with the<br>
>>> remote control working in a different application.<br>
>><br>
>> MythTV supports DVD menus for compliant DVDs. Disney is notorious for<br>
>> creating non-compliant DVDs using structural protection (i.e. errors on the<br>
>> disc) to prevent copying. Generally, a player (hardware or software) will<br>
>> play a DVD with structural protection without problems because the<br>
>> navigation information keeps the player from reading the "broken" data.<br>
>> Ripping the disc, however, entails copying all the data on the disc--which<br>
>> means you'd attempt to read the broken data and get an error. This is why<br>
>> you had to use the hack you referenced to attempt to rip the disc. However,<br>
>> I wouldn't be surprised to learn that the rip of such a CD is unplayable by<br>
>> MythTV (we have no code, whatsoever, to try to work around<br>
>> copyright-protection mechanisms--including structural protection--even<br>
>> though many (most?) other DVD player packages do).<br>
>><br>
>> So, I'd recommend sticking the actual disc in the drive and attempting to<br>
>> play it with MythTV. If it works, that means that the approach you had to<br>
>> use to rip the broken DVD gave you an even-more-broken rip. You can then<br>
>> take the disc back to the store and tell them you're returning it because<br>
>> it's not compliant with the DVD specification, so it can't be played on your<br>
>> player. If playback of the original disc doesn't work, it may or may not be<br>
>> the structural protections causing problems in MythTV--you'd probably have<br>
>> to dig deep into the code and the actual disc/playback to find out what's<br>
>> happening and whether it's a MythTV bug or a non-compliant disc that's<br>
>> causing the failure. (And remember that other DVD playback software does<br>
>> try to incorporate workarounds for protected discs--so just because it works<br>
>> in<insert DVD player name>, doesn't mean that it's not the structural<br>
>> protection or that it's a compliant disc.)<br>
>><br>
> All of what you say is clearly correct, but what I have never been<br>
> able to work out is how even quite old STB DVD players cope with all<br>
> these broken disney (and other manufacturer) disks (assuming they do,<br>
> mine has been sitting in the garage for a while now).<br>
<br>
Because a) the navigation information in the disc prevents the player<br>
from ever attempting to read the errored parts on the disc (as mentioned<br>
above) and b) most non-computer DVD players do not return errors that<br>
cause failure when they do stumble across an error on a disc (they were<br>
designed this way to help them be more resilient to scratched discs,<br>
causing just playback glitches rather than failures). Computer drives,<br>
however, are designed to get exact information from discs and keep<br>
retrying when they see errors and report errors when they eventually<br>
decide they can't read a portion. (Also note that generally the<br>
cheapest DVD player hardware tends to be the most resilient--to allow<br>
the manufacturer to create a product that's most likely to work without<br>
having to test as extensively for compliance--so quality of the DVD<br>
player may not affect results in the way one would think.)<br>
<br>
See also <a href="http://en.wikipedia.org/wiki/ARccOS_Protection" target="_blank">http://en.wikipedia.org/wiki/ARccOS_Protection</a> for more info on<br>
one such implementation of structural protection.<br>
<br>
That's why I'm guessing that playing the actual disc will work and it's<br>
just the "even-more-errored-than-the-(broken-by-design)-disc" rip that's<br>
likely causing problems.<br>
<br>
Mike<br>
<br>
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