[FFmpeg-trac] #2224(undetermined:new): HLS output using b-frames has crazy initial timestamps

FFmpeg trac at avcodec.org
Mon Apr 1 17:36:06 CEST 2013

#2224: HLS output using b-frames has crazy initial timestamps
             Reporter:  nealzebub    |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  unspecified  |  undetermined
             Keywords:  libx264      |               Resolution:
  mpegts hls                         |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |

Comment (by nealzebub):

 I do not know if Wowza output produces Warnings in Validator, but I
 suspect not, since that is why they implemented the 10-second timestamp
 offset in version 3.5+.  I also suspect that they offset by 10 seconds to
 avoid the following two mediastreamvalidator issues reported.

 1. Error - due to a negative timestamps, which is interpreted as a really
 high value.  Validator reports decreasing timestamps.  If the the first
 PTS is zero, then the first DTS is probably less than zero.

 2. Warning - Validator, for some reason, is unable to read frames with a
 timestamp of zero.

 To be clear, a stream produced by FFmpeg using -avoid_negative_ts 1 can
 produce #2, the warning.

 Looking at the Wowza forums, it reads that Wowza was resistant to setting
 the offset in February 2012.  Then, in November 2012, the builds have the
 offset by default.

 I re-quote the Wowza thread from Sept 2012:
 Below is the comment from one of the staff at Apple @baleighsdad:

 However, I'm not sure where Wowza got their information; I don't recommend
 using a 0 PTS in the first segment, and have said many times that this
 isn't a good idea. Our own tools using a starting PTS of the equivalent of
 10 seconds, to avoid wrap."

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2224#comment:8>
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