Re: [yavta PATCH 7/9] Print timestamp type and source for dequeued buffers

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

On Friday 11 April 2014 01:36:03 Sakari Ailus wrote:
> Laurent Pinchart wrote:
> > On Thursday 10 April 2014 21:58:41 Sakari Ailus wrote:
> >> Laurent Pinchart wrote:
> >>> Hi Sakari,
> >>> 
> >>> Thank you for the patch.
> >>> 
> >>> Given that the timestamp type and source are not supposed to change
> >>> during streaming, do we really need to print them for every frame ?
> >> 
> >> When processing frames from memory to memory (COPY timestamp type), the
> >> it is entirely possible that the timestamp source changes as the flags
> >> are copied from the OUTPUT buffer to the CAPTURE buffer.
> > 
> > It's possible, but is it allowed by the V4L2 API ?
> 
> The spec states that:
> 
> "The V4L2_BUF_FLAG_TIMESTAMP_COPY timestamp type which is used by e.g. on
> mem-to-mem devices is an exception to the rule: the timestamp source flags
> are copied from the OUTPUT video buffer to the CAPTURE video buffer."
> 
> >> These patches do not support it but it is allowed.
> >> 
> >> One option would be to print the source on every frame only when the
> >> type is COPY. For a program like yavta this might be overly
> >> sophisticated IMO. :-)
> > 
> > My concern is that this makes the lines output by yavta pretty long.
> 
> True as well. I could remove "type/src " from the timestamp source
> information. That's mostly redundant anyway. Then we shouldn't exceed 80
> characters per line that easily anymore.

I think that would be better.
 
> Could this be the time to add a "verbose" option? :-)

Possibly, but then we'll need to discuss what information should be printed in 
verbose mode only :-)

-- 
Regards,

Laurent Pinchart