[mpeg2] Re: Setting Audio, Video, and PCR PIDs

[Andrew de Quincey <adq_dvb@lidskialf.net>]

> > We should probably use the in-kernel crc32 library...
>
> Opss... I did not know about it ;) New patch attached. I hope I used the
> kernel crc routine in the correct way - ffmpeg likes the PATs and PMTs
> produced by the new code, hence it seems that the crc is computed
> correctly.

Cool.

> Ok. I noticed it because I was calling the MPEG_SETPARAMS ioctl()
> without setting video_max_bitrate (I was setting bitrate_mode =
> MPEG_BITRATE_MODE_CBR), and the ioctl was not working.
>
> BTW, there is a bug that I forgot to mention: if the checks in
> saa6752hs_init() fail, the ioctl() fails silently (i.e., the return
> value is not negative). Since saa6752hs_init() is properly returning a
> negative value, I think the problem is somewhere else... Uhm.. I think I
> am seeing it: ts_init_encoder() in drivers/media/video/saa7134-ts.c is
> always returning 0!!! Can we get a return value from
> saa7134_i2c_call_clients()? Ok, I'll try to have a look at it...

Ah, yeah, as far as I know it isn't possible. It seems to be a bit of a flaw 
in the i2c stuff really. I think the best we can do for the moment is bung 
something in dmesg if something fails.

> > > Now, I am thinking about adding code for setting the video format (it
> > > is currently hardcoded to D1). Is it ok to add yet another field to
> > > mpeg_params?
> >
> > Fine by me - if you can, try and make it flexible; I was aiming for
> > something that used by other MPEG encoders at a future date.
>
> Unfortunately, I don't know about other MPEG encoders... I see that in
> the saa6752hs there is a 1-byte parameter for selecting the video format
> (D1, 2/3D1, 1/2D1, or SIF) and I was thinking about adding a field to
> mpeg_params for setting the format. But I don't know if this is flexible
> enough.

Sounds fine - it can always be sorted out if/when another MPEG encoder 
appears.

> Finally, I also have a patch against saa7134-ts.c, for transforming
> TS_NR_PACKETS in a module parameter (very useful for reducing the jitter
> in the PCR!!!), and I wanted to submit it to Gerd Knorr, but it seems
> that the v4l mailing list is not working (or I have been unsubscribed
> for some reason, I don't know). I attach it to this mail; maybe you can
> submit it when you will submit the next update to saa6752hs.c?

Sure, no probs.