Hi Kamil, Sakari, thank you for your replies. On 15 March 2012 14:19, Kamil Debski <k.debski@xxxxxxxxxxx> wrote: > Hi Javier, Sakari, > >> From: Sakari Ailus [mailto:sakari.ailus@xxxxxx] >> Sent: 15 March 2012 12:04 >> >> Hi Javier, >> >> (Cc Kamil.) >> >> On Wed, Mar 14, 2012 at 12:22:43PM +0100, javier Martin wrote: >> > Hi, >> > I'm developing a V4L2 mem2mem driver for the codadx6 IP video codec >> > which is included in the i.MX27 chip. >> > >> > The capture interface of this driver can therefore return h.264 or >> > mpeg4 video frames. >> > >> > Provided that the size of each frame varies and is unknown to the >> > user, how is the driver supposed to react to a S_FMT when it comes to >> > parameters such as the following? >> > >> > pix->width >> > pix->height >> > pix->bytesperline >> > pix->sizeimage >> > >> > According to the documentation [1] I understand that the driver can >> > just ignore 'bytesperline' and should return in 'sizeimage' the >> > maximum buffer size to store a compressed frame. However, it does not >> > mention anything special about width and height. Does it make sense >> > setting width and height for h.264/mpeg4 formats? >> > > Yes, in case of the compressed side (capture) the width, height and > bytesperline > is ignored. The MFC driver sets bytesperline to 0 and leaves width and height > intact > during S_FMT. I suggest you do the same or set all of them (width, height, > bytesperline) > to 0. I'm not sure about that, according to the code in here [1] it ignores width and height, as you stated, but it fills bytesperline with the value in imagesize. This applies to TRY_FMT and S_FMT. On the other hand, in G_FMT [2], it sets width and height to 0, but bytesperline and sizeimage are set to ctx->enc_dst_buf_size, which I deduce it's the encoder buffer size. If this is the agreed way of doing things I can just implement this behavior in my driver as well. Regards. [1] http://lxr.linux.no/#linux+v3.2.11/drivers/media/video/s5p-mfc/s5p_mfc_enc.c#L880 [2] http://lxr.linux.no/#linux+v3.2.11/drivers/media/video/s5p-mfc/s5p_mfc_enc.c#L844 -- Javier Martin Vista Silicon S.L. CDTUC - FASE C - Oficina S-345 Avda de los Castros s/n 39005- Santander. Cantabria. Spain +34 942 25 32 60 www.vista-silicon.com -- 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
