search

ut0mt8 / nginx-rtmp-module

NGINX-based Media Streaming Server
http://nginx-rtmp.blogspot.com
BSD 2-Clause "Simplified" License
87 stars 32 forks source link

Time Base #3

Closed ReubenM closed 7 years ago

ReubenM commented 7 years ago

I've been testing this and I have a 30000/1001 scan rate stream where the rate is being written with a 1000 frame base:

frameRate="29969/1000" timescale="1000"

I'm trying to figure out why player.time() in dash.js does not match the actual time of the video. Doing a player.seek( 0 ) seems to have dash.js loose it's marbles as to where it is at, and I was wondering if the timescale at 1000 rather than 1001 might contribute to that.

ReubenM commented 7 years ago

Looking at ffmpeg's output, it uses the frame rate as the timescale, so for the 30000/1001 scan rate video (with 48k audio) it generates the following:

Video: Representation frameRate="30000/1001" SegmentTemplate timescale="30000"

Audio: Representation audioSamplingRate="48000" SegmentTemplate timescale="48000"

ut0mt8 commented 7 years ago

The timescale written by nginx-rtmp is always with a timescale a 1000. It was not relative to my fork. I suggest you to open an issue to the serguei github. btw : I ve use dashjs and have some issues too with timing operations...

ReubenM commented 7 years ago

Well I figured out the framerate part: In ngx_rtmp_dash_module.c the "case 29970:" was not evaluating to true because it was 29969. Fixed that.

I wasn't aware the timescale was hardcoded. For some reasons I thought I it had output something different in the past. Guess it does help to actually read the code. Sorry to pester you.

I patched ffmpeg to output valid dynamic dash, and the time/duration numbers in dash.js play nice with it. With the nginx-rtmp-dash, I would get weird numbers that were out of range of what it should have been, as well as the occasional NAN.

ut0mt8 commented 7 years ago

OK thanks for the info. If you read the code you will note that all timescale is hardcode to 1000. This is bad; but work for most case.