[Live-devel] How to get the time_scale value from H264/RTSP stream

[Sergio Basurco]

So,

I found that as I'm using RTP, a clock rate of 90000Hz must be used. In 
some cases cameras specify a different clock rate... but if none is 
specified I should be using that one.

My problem now, is that I do get timestamps for the NAL units, but I 
don't know the timestamp of my decoded frame... In libav there's two 
timestamps dts (decoding timestamp) and pts (presentation timestamp).

Say that for a given decoded frame I sent 4 NAL units to the decoder. 
Each one had its presentationTime set by Live555. Which of those times 
should I use for my frame if any?

Saludos / Best regards,

*Sergio Basurco*
Coherent Synchro

On 28/09/2017 16:34, Sergio Basurco wrote:
>
> Hi,
>
> My goal is to play an H264 stream that comes from a camera. I am 
> decoding using libav. According to H264 standard, it is not necessary 
> to specify the time_scale info in the SDP/SPS.
>
> Everything is working fine, however I need to synchronize playback to 
> prevent stutters. I am parsing the nal units in my H264Sink, in which 
> I get a presentationTime (timeval). What I don't have is the timebase 
> for these timestamps.
>
> From what I can tell, the timebase / time_scale of the timestamps 
> provided by Live555 must be available somewhere for me to set it to my 
> decoder. If it's not in the SPS description, how can I retrieve it?
>
> -- 
>
> Saludos / Best regards,
>
> *Sergio Basurco*
> Coherent Synchro
>
>
>
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