Add ability to determine presentation timestamp about picamera

[martinohanlon]

I was thinking something similar and grouping encoder_data together. I was actually thinking a static class with properties but a tuple would be a simpler implementation. I share your thoughts though that frame should probably be renamed.

[waveform80]

FYI, a namedtuple (derived from tuple) basically is a static class with properties (its implementation in the collections module is a bit of a hack that involves eval() but to be honest I couldn't come up with a better way of designing it :). Still, that sounds like the way to go - and makes future expansion of the facility easy as I can just extend the namedtuple with more fields.

What source of encoder data were you hoping to combine with this? If they're equally easy to grab I'm more than happy to extend the ticket to include them.

[martinohanlon]

I see, namedtuple does sound like the way to go. Other data that springs to mind, although it might not be easily accessible:

• size, total size of the video
• length
• dropped frames

[waveform80]

Size is certainly possible - I'll add properties for the size of the current frame and the total size of the video recorded so far (bytes). It should also be possible to add a property for the size of video since the last call to split_recording().

Isn't length (which I'm assuming is the duration of the video recorded so far) equivalent to PTS? I'll have to experiment with this a bit and see if the reading from the pts field in the buffer header starts to vary from the wall-clock.

Not sure about dropped frames - picamera itself has no facility for dropping frames in the case of over-run - it rather dumbly assumes that whatever stream the user gives it is capable of handling the throughput. As far as I'm aware there's no facility for asking MMAL if the encoder's dropped any frames either - but if you know of one I'm happy to look into it.