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• How to set "ch_layout" in ffmpeg 6.1 ?

  9 juillet 2024, par Steven porite

  In 6.1 Ffmpeg, it use "ch_layout" to replace the "channel_layout" and "number". The "ch_layout" is "AVChannelLayout *" type. This type is defined in channel_layout.h, some kind of "ch_layout" is defined in this file too.
If I want to use the "av_dict_set_int()" set the "ch_layout" to "AV_CHANNEL_LAYOUT_STEREO", what should I fill to the "value" ?

  


  /**
 * Macro to define native channel layouts
 *
 * @note This doesn't use designated initializers for compatibility with C++ 17 and older.
 */
#define AV_CHANNEL_LAYOUT_MASK(nb, m) \
    { /* .order */ AV_CHANNEL_ORDER_NATIVE, \
      /* .nb_channels */  (nb), \
      /* .u.mask */ { m }, \
      /* .opaque */ NULL }

/**
 * @name Common pre-defined channel layouts
 * @{
 */
#define AV_CHANNEL_LAYOUT_MONO              AV_CHANNEL_LAYOUT_MASK(1,  AV_CH_LAYOUT_MONO)
#define AV_CHANNEL_LAYOUT_STEREO            AV_CHANNEL_LAYOUT_MASK(2,  AV_CH_LAYOUT_STEREO)
#define AV_CHANNEL_LAYOUT_2POINT1           AV_CHANNEL_LAYOUT_MASK(3,  AV_CH_LAYOUT_2POINT1)
#define AV_CHANNEL_LAYOUT_2_1               AV_CHANNEL_LAYOUT_MASK(3,  AV_CH_LAYOUT_2_1)


  


  /**
 * Convenience wrapper for av_dict_set() that converts the value to a string
 * and stores it.
 *
 * Note: If ::AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error.
 */
int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags);


  


• avcodec/wavpackenc : add support for encoding unspec channel layouts

  14 août 2023, par Paul B Mahol

  avcodec/wavpackenc : add support for encoding unspec channel layouts
  Also write 0 for chmask if mask have bits outside of first 32 bits,
  
  as wavpack does not support more bits than 32 for channel layouts.
  

  • [DH] libavcodec/wavpackenc.c

• Revision f5209d7e01 : Remove rate component adjustment for AQ1 In AQ1 a rate adjustment was applied f

  21 novembre 2014, par Paul Wilkins

  Changed Paths :
   Modify /vp9/encoder/vp9_encodeframe.c

  
  
  Remove rate component adjustment for AQ1

  In AQ1 a rate adjustment was applied for blocks coded with a
  deltaq. This tends to skew the partition selection and cause
  rate overshoot.

  For example, consider a 64x64 super block where some but not all
  sub blocks are in a low q segment and some are in a high q segment.
  The choice of Q when considering large partition and transform sizes
  is defined by the lowest sub block segment id (currently this implies the
  lowest Q). If some parts of the larger partition are very hard this will
  cause a high rate component.

  The correct behavior here is for the rd code to discard the large partition
  choice and break down to sub blocks where some have low and some
  have high Q. However the rate correction factor above mask the high
  cost of coding at a larger partition size.

  Change-Id : Ie077edd0b1b43c094898f481df772ea280b35960