On Mon 9 September 2013 11:09:57 Sylwester Nawrocki wrote: > On 09/09/2013 11:00 AM, Kamil Debski wrote: > [...] > >>>> We have QP controls separately for H264, H263 and MPEG4. Why is that? > >>>> Which one should I use for VP8? Shouldn't we unify them instead? > >>> > >>> I can't quite remember the details, so I've CCed Kamil since he added > >> those controls. > >>> At least the H264 QP controls are different from the others as they > >>> have a different range. What's the range for VP8? > >> > >> Yes, it differs, 0-127. > >> But I feel this is pretty unfortunate, is it a good idea to multiply > >> controls to have one per format when they have different ranges > >> depending on the selected format in general? Perhaps a custom handler > >> would be better? > >> > >>> I'm not sure why the H263/MPEG4 controls weren't unified: it might be > >>> that since the > >>> H264 range was different we decided to split it up per codec. But I > >>> seem to remember that there was another reason as well. > > > > We had a discussion about this on linux-media mailing list. It can be found > > here: > > http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructure/32606 > > In short, it is a mix of two reasons: one - the valid range is different for > > different formats and second - implementing controls which have different > > min/max values depending on format was not easy. > > Hmm, these seem pretty vague reasons. And since some time we have support > for dynamic control range update [1]. I don't think we should change this. We chose to go with separate controls, and we should stick with that. We might do it differently today, but it's not a big deal. Regards, Hans > > > On the one hand I am thinking that now, when we have more codecs, it would > > be better > > to have a single control, on the other hand what about backward > > compatibility? > > Is there a graceful way to merge H263 and H264 QP controls? > > [1] https://patchwork.linuxtv.org/patch/16436/ > > -- > Regards, > Sylwester > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
