[FFmpeg-devel] hls BANDWIDTH field in master playlist
amitk at hotstar.com
Thu Feb 1 15:29:30 EET 2018
Thanks for this info. Will soon get back with a patch.
On 01-Feb-2018 3:58 PM, "Jeyapal, Karthick" <kjeyapal at akamai.com> wrote:
> On 2/1/18 3:12 PM, Amit Kale wrote:
> > Hi All,
> > When emitting a master playlist, BANDWIDTH field is computed in
> > libavformat/hlsenc.c by adding video and audio stream bitrates and then
> > adding 10% to account for container overhead. However HLS specification
> > (RFC8216) says that BANDWIDTH represents the peak segment bit rate.
> > AVERAGE-BANDWIDTH on the other hand represents the average segment bit
> > rate. If this is correct, I would like to send a patch to fix it.
> Yes, you are right. Ofcourse, you are welcome to send a patch to fix it.
> But please keep the following in mind, while sending the patch
> - BANDWIDTH is mandatory parameter and AVERAGE-BANDWIDTH is optional
> - Master playlist gets created at the beginning of encode during which
> time we neither know the peak bitrate or the average bitrate of the stream.
> Right now, we are just using the codec’s bitrate parameter which could be
> way different from the actual bitrate of the stream. So the master
> playlist should get created initially with BANDWIDTH as codec bitrate(to
> handle live encode). At the end of encoding, master playlist should be
> updated again with the true peak bitrate and true average bitrate(for
> - The definition for BANDWIDTH changed to peak bitrate only in v7 of the
> HLS spec. Earlier BANDWIDTH was mentioned as overall bitrate. So, there
> should be an option to turn on or turn off peak bitrate calculation.
> > Thanks.
> > -Amit
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