[Linphone-developers] H.263 bitstream syntax error ; an FFMPEG problem?

[Francois-Xavier KOWALSKI]

Folks,

FYI, the H.263 video bitstream generated by FFMPEG is an H.263-1998 with 
a syntax error in the picture header. This error is located in the 
mandatory PTYPE bitfield. It may cause H.263 decoder to abort the stream.

   ----------H.263+ : MANDATORY PLUS PTYPE----------
   pict_type: 000(0)
   reference_picture_resampling_mode: 0(0)
   reduced_resolution_update_mode: 0(0)
   rounding_type: 0(0)
   rtype: 0(0)
   reserve, reserve, spare: *101*(5) <= should be 001(1)

The H.263 specs (I checked from H.263v1 to H.263v3) states the following:

   5.1.4.3 The mandatory part of PLUSPTYPE when PLUSPTYPE present (MPPTYPE)
   (9 bits)
   Regardless of the value of UFEP, the following 9 bits are also
   present in PLUSPTYPE:
   – Bits 1-3 Picture Type Code:
   "000" I-picture (INTRA),
   "001" P-picture (INTER),
   "010" Improved PB-frame (see Annex M),
   "011" B-picture (see Annex O),
   "100" EI-picture (see Annex O),
   "101" EP-picture (see Annex O),
   "110" Reserved,
   "111" Reserved;
   – Bit 4 Optional Reference Picture Resampling (RPR) mode (see Annex
   P), "0" off,
   "1" on;
   – Bit 5 Optional Reduced-Resolution Update (RRU) mode (see Annex Q),
   "0" off, "1"
   on;
   – Bit 6 Rounding Type (RTYPE) (see 6.1.2);
   *– Bit 7 Reserved, shall be equal to "0";
   – Bit 8 Reserved, shall be equal to "0";
   – Bit 9 Equal to "1" to prevent start code emulation.*

--
Francois-Xavier "FiX" KOWALSKI     /_ __  Tel:+33 (0)4 76 14 63 27
OpenCall Business Unit -- OCBU    / //_/  Fax:+33 (0)4 76 14 51 62
Media-Processing Engineering        /     http://www.hp.com/go/opencall
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