[FFmpeg-user] Libnvenc live transcode mpeg2 to x264 hls missing key frames?

Moritz Barsnick barsnick at gmx.net
Fri Feb 5 10:11:22 CET 2016


On Thu, Feb 04, 2016 at 23:10:08 -0500, Subscriptions at znet.ca wrote:

Minor complaint:

> ggeorgiev at gtx690:/var/www/iptv/html$ ffprobe m3u/TEST2/TS-x2645.ts
> ffprobe version 2.4.git Copyright (c) 2007-2014 the FFmpeg developers
>    built on Dec 21 2015 20:16:32 with gcc 4.9.2 (Debian 4.9.2-10)
>    configuration: --enable-libnvenc --enable-libfaac --enable-libfdk-aac --enable-librtmp --enable-libx264 --enable-gpl --enable-nonfree
>    libavutil      54. 10.100 / 54. 10.100
>    libavcodec     56.  8.102 / 56.  8.102
>    libavformat    56.  9.101 / 56.  9.101
>    libavdevice    56.  1.100 / 56.  1.100
>    libavfilter     5.  1.106 /  5.  1.106
>    libswscale      3.  1.101 /  3.  1.101
>    libswresample   1.  1.100 /  1.  1.100
>    libpostproc    53.  3.100 / 53.  3.100

If I'm not totally mistaken, this version of ffmpeg is from around
October 2014. Could you also please test a newer version?

> So, how it can be that key frames are invisible in the output produced 
> by libnvenc? And if so, how the stream can be played normally if there 
> are no key frames in it?

Some sources on StackOverflow, which may or may not be correct, claim
that Apple HLS indeed requires keyframes in each new segment.
http://stackoverflow.com/q/11640072
http://stackoverflow.com/a/11644887 (answer to the question above).

I have no idea though, nor how to get ffmpeg and/or nvenc to ensure
this.

Moritz


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