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]. > 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
