On 09/30/14 16:20, Philipp Zabel wrote: > Hi Hans, > > Am Dienstag, den 30.09.2014, 15:43 +0200 schrieb Hans Verkuil: >> On 09/30/14 11:57, Philipp Zabel wrote: >>> Hi, >>> >>> These patches add JPEG encoding and decoding support for CODA7541 (i.MX5). >>> The encoder video device is split into one video device per codec, so that >>> each video device can register only the relevant controls. The H.264/MPEG4 >>> decoder is kept as one video device, but the JPEG decoder video device is >>> separate because it supports more uncompressed formats (currently YUV422P, >>> in the future grayscale or YUV 4:4:4 support could be added). >> >> Normally device nodes are linked to DMA engines, so the only reason why you >> would have e.g. two video nodes is if you can capture from both at the same >> time. Is that the case here as well? If not, then it really should be a >> single video node. That not all controls are relevant for the currently >> chosen codec is not important. >> >> Are there other reasons than the controls to split it up into multiple video >> devices? > > I had already split the encoder and decoder parts of this mem2mem device > into two video devices because of the issue of changing available > capture formats depending on the selected output format. > The motivation for splitting the JPEG codecs from the H264/MPEG4 codecs > is the same: to avoid the appearing and disappearing of the YUV422P > format on the uncompressed side whenever the compressed format changes > between JPEG and H264/MPEG4. I could keep the H264 and MPEG4 encoders > combined without running into this issue. > > Furthermore, I want to change the output queue for the currently > available decoders to use vb2-vmalloc eventually (because the CPU has to > copy incoming frames into the bitstream buffer), but have to keep using > vb2-dma-contig for the CODA960 JPEG decoder, which will have the > hardware read from the incoming buffers directly. Based on this description I think it makes sense to split off the JPEG encoder, but I would keep H264/MPEG4 together. Kamil, what's your opinion on this? Regards, Hans -- 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
