[FFmpeg-user] vp9 generates frames with strange PTS

Sagara Wijetunga sagarawmw at yahoo.com
Mon Sep 29 14:06:59 CEST 2014

Further to the issue I highlighted.
1. Same player for vp8 generates only I and P frames with correct PTS values.
2. For vp9, the same player also generates I and P frames. But there are lot of wrong P frames generated in between correct P frames.
Eg.PTS = 0.000 (Correct)    PTS = 0.001 (wrong)
    PTS = 0.013 (wrong)
    PTS = 0.019 (wrong)
    PTS = 0.024 (wrong)
    PTS = 0.030 (wrong)
    PTS = 0.036 (wrong)
PTS = 0.042 (Correct)

This is a file with 23.98 tbr.
I use avcodec_decode_video2();
The (AVFrame->pkt_pts * video-stream-TimeBase (ie. tbn)) is used for PTS.

     On Sunday, September 28, 2014 12:56 AM, Sagara Wijetunga <sagarawmw-at-yahoo.com at ffmpeg.org> wrote:

I use the latest ffmpeg (2.4.1) libs and the ffvp9 decoder.
I get decoded frames with strange PTS values as follows:
PTS: 0.000PTS: 0.001PTS: 0.083PTS: 0.125PTS: 0.167PTS: 0.209PTS: 0.250PTS: 0.036PTS: 0.078PTS: 0.119PTS: 0.161PTS: 0.203PTS: 0.245PTS: 0.030PTS: 0.072PTS: 0.114PTS: 0.155PTS: 0.197PTS: 0.239PTS: 0.024PTS: 0.066PTS: 0.108PTS: 0.150PTS: 0.191PTS: 0.233PTS: 0.019PTS: 0.020PTS: 0.102PTS: 0.144PTS: 0.186PTS: 0.227PTS: 0.013PTS: 0.055PTS: 0.096PTS: 0.138PTS: 0.180PTS: 0.222PTS: 0.223PTS: 0.049PTS: 0.091PTS: 0.132PTS: 0.174PTS: 0.216PTS: 0.001PTS: 0.043PTS: 0.085PTS: 0.127PTS: 0.168PTS: 0.210PTS: 0.252PTS: 0.037
Note values are in seconds.
Note, I get frames with PTS 0.001 and 0.002. That is only a one millisecond apart!
Same video in vp8 using ffvp8 generates frames with PTS values as follows:
PTS: 0.000PTS: 0.042PTS: 0.083PTS: 0.125PTS: 0.167PTS: 0.209PTS: 0.250PTS: 0.292PTS: 0.334PTS: 0.375PTS: 0.417PTS: 0.459PTS: 0.501PTS: 0.542PTS: 0.584PTS: 0.626PTS: 0.667PTS: 0.709PTS: 0.751PTS: 0.792PTS: 0.834PTS: 0.876PTS: 0.918PTS: 0.959PTS: 1.001PTS: 1.043PTS: 1.084PTS: 1.126PTS: 1.168PTS: 1.210PTS: 1.251PTS: 1.293PTS: 1.335PTS: 1.376PTS: 1.418PTS: 1.460PTS: 1.502PTS: 1.543PTS: 1.585PTS: 1.627PTS: 1.668PTS: 1.710PTS: 1.752PTS: 1.793PTS: 1.835PTS: 1.877PTS: 1.919PTS: 1.960PTS: 2.002PTS: 2.044PTS: 2.085
The same vp9 video plays very well in ffplay.
It looks like something required to be set in my player.
Any ideas? 
Thanks in advance.
Best regardsSagara
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