Re: [Libcdio-devel] Fedora bug report concerning CD-TEXT

[Leon Merten Lohse]

On Sun, 03 Apr 2016 12:27:22 +0200
"Thomas Schmitt" <address@hidden> wrote:

> There is an overall problem lurking at the horizon:
>  
> - The command READ SUB-CHANNEL is not part of MMC-5 and MMC-6 any
> more. MMC-5 was released in 2007.
>   cdrdao scans the sub-channel data which are replied by READ CD when
>   reading the whole track.
>   One could stop reading when the first instance of MCN or ISRC is
> found in the track. MMC-5 7.5.4.18, 7.5.4.19 promise that one has to
> read at most 100 blocks in order to get such an instance.

Thanks for pointing that out. MMC-5 reads like the READ SUB-CHANNEL
command was part of the `CD Audio External Play' feature set, which
clearly is outdated.

> Well, exchanging READ SUB-CHANNEL by a READ CD scan loop is a larger
> job from which i refrain for now.

I think we can safely postpone that for now. But eventually it should
be implemented.

> [...]
 
> I wonder whether it would be desirable to unite both function bodies.

Feels like the way to go to me as both use READ SUB-CHANNEL.

> In another stage of metamorphosis, we could split the new function
> into an SCSI transport part and an MMC interpreter part, in order to
> avoid requesting more reply bytes than the drive might be willing to
> return.
> This might be necessary to avoid problems with operating system SCSI
> passthrough drivers. (There once were and there might still be in
> Linux.)

I really hope that this has become unnecesary in the year 2016.

Thanks for all the work you did so far!

Best Regards
Leon