[FFmpeg-trac] #3393(undetermined:open): Interlaced H.264 packets are split causing MP4 STTS
FFmpeg
trac at avcodec.org
Fri Mar 21 08:57:06 CET 2014
#3393: Interlaced H.264 packets are split causing MP4 STTS
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Reporter: wim_arbor | Owner:
Type: defect | Status: open
Priority: normal | Component:
Version: git-master | undetermined
Keywords: h264 mov | Resolution:
Blocking: | Blocked By:
Analyzed by developer: 0 | Reproduced by developer: 1
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Comment (by wim_arbor):
What I understand from the discussion on the mailing list is that merging
the fields into field pairs violates the ISO specification.
> AVC sample: An AVC sample is an access unit as defined in ISO/IEC
14496‐10
> access unit: A set of NAL units that are consecutive in decoding order
and contain exactly one primary coded picture. (...) The decoding of an
access unit always results in a decoded picture.
Each (PAFF) field is encoded as a separate picture, so a sample in a MP4
file may only contain a single field.
So software which uses the sample count in the MP4 file to determine the
frame rate is simply wrong. This includes mediainfo, vlc, quicktime and
gspot. The same applies to other encoders which generate such files. I
tested sorenson squeeze with the intel and mainconcept encoder. Both
merged fields.
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Ticket URL: <https://trac.ffmpeg.org/ticket/3393#comment:7>
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