Newlib static and shared object port of libVPX, a freely available and
open-source video codec.

Difficult to port. Instructions on how to port future versions of libVPX are
included.

vpxenc / vpxdec tested and included as example programs.

Modified source is included. Simply extract, "sh" and "Make" (make an assign to
"Other:" first). Read the how-to guide before compiling.

Changes (general):

2012-05-09 v1.1.0 "Eider"
  This introduces a number of enhancements, mostly focused on real-time
  encoding. In addition, it fixes a decoder bug (first introduced in
  Duclair) so all users of that release are encouraged to upgrade.

  - Upgrading:
    This release is ABI and API compatible with Duclair (v1.0.0). Users
    of older releases should refer to the Upgrading notes in this
    document for that release.

    This release introduces a new temporal denoiser, controlled by the
    VP8E_SET_NOISE_SENSITIVITY control. The temporal denoiser does not
    currently take a strength parameter, so the control is effectively
    a boolean - zero (off) or non-zero (on). For compatibility with
    existing applications, the values accepted are the same as those
    for the spatial denoiser (0-6). The temporal denoiser is enabled
    by default, and the older spatial denoiser may be restored by
    configuring with --disable-temporal-denoising. The temporal denoiser
    is more computationally intensive than the spatial one.

    This release removes support for a legacy, decode only API that was
    supported, but deprecated, at the initial release of libvpx
    (v0.9.0). This is not expected to have any impact. If you are
    impacted, you can apply a reversion to commit 2bf8fb58 locally.
    Please update to the latest libvpx API if you are affected.

  - Enhancements:
      Adds a motion compensated temporal denoiser to the encoder, which
      gives higher quality than the older spatial denoiser. (See above
      for notes on upgrading).

      In addition, support for new compilers and platforms were added,
      including:
        improved support for XCode
        Android x86 NDK build
        OS/2 support
        SunCC support

      Changing resolution with vpx_codec_enc_config_set() is now
      supported. Previously, reinitializing the codec was required to
      change the input resolution.

      The vpxenc application has initial support for producing multiple
      encodes from the same input in one call. Resizing is not yet
      supported, but varying other codec parameters is. Use -- to
      delineate output streams. Options persist from one stream to the
      next.

      Also, the vpxenc application will now use a keyframe interval of
      5 seconds by default. Use the --kf-max-dist option to override.

  - Speed:
      Decoder performance improved 2.5% versus Duclair. Encoder speed is
      consistent with Duclair for most material. Two pass encoding of
      slideshow-like material will see significant improvements.

      Large realtime encoding speed gains at a small quality expense are
      possible by configuring the on-the-fly bitpacking experiment with
      --enable-onthefly-bitpacking. Realtime encoder can be up to 13%
      faster (ARM) depending on the number of threads and bitrate
      settings. This technique sees constant gain over the 5-16 speed
      range. For VC style input the loss seen is up to 0.2dB. See commit
      52cf4dca for further details.

  - Quality:
      On the whole, quality is consistent with the Duclair release. Some
      tweaks:

        Reduced blockiness in easy sections by applying a penalty to
        intra modes.

        Improved quality of static sections (like slideshows) with
        two pass encoding.

        Improved keyframe sizing with multiple temporal layers

  - Bug Fixes:
      Corrected alt-ref contribution to frame rate for visible updates
      to the alt-ref buffer. This affected applications making manual
      usage of the frame reference flags, or temporal layers.

      Additional constraints were added to disable multi-frame quality
      enhancement (MFQE) in sections of the frame where there is motion.
      (#392)

      Fixed corruption issues when vpx_codec_enc_config_set() was called
      with spatial resampling enabled.

      Fixed a decoder error introduced in Duclair where the segmentation
      map was not being reinitialized on keyframes (#378)


2012-01-27 v1.0.0 "Duclair"
  Our fourth named release, focused on performance and features related to
  real-time encoding. It also fixes a decoder crash bug introduced in
  v0.9.7, so all users of that release are encouraged to upgrade.

  - Upgrading:
      This release is ABI incompatible with prior releases of libvpx, so the
      "major" version number has been bumped to 1. You must recompile your
      applications against the latest version of the libvpx headers. The
      API remains compatible, and this should not require code changes in most
      applications.

  - Enhancements:
      This release introduces several substantial new features to the encoder,
      of particular interest to real time streaming applications.

      Temporal scalability allows the encoder to produce a stream that can
      be decimated to different frame rates, with independent rate targetting
      for each substream.

      Multiframe quality enhancement postprocessing can make visual quality
      more consistent in the presence of frames that are substantially
      different quality than the surrounding frames, as in the temporal
      scalability case and in some forced keyframe scenarios.

      Multiple-resolution encoding support allows the encoding of the
      same content at different resolutions faster than encoding them
      separately.

  - Speed:
      Optimization targets for this release included the decoder and the real-
      time modes of the encoder. Decoder speed on x86 has improved 10.5% with
      this release. Encoder improvements followed a curve where speeds 1-3
      improved 4.0%-1.5%, speeds 4-8 improved <1%, and speeds 9-16 improved
      1.5% to 10.5%, respectively. "Best" mode speed is consistent with the
      Cayuga release.

  - Quality:
      Encoder quality in the single stream case is consistent with the Cayuga
      release.

  - Bug Fixes:
      This release fixes an OOB read decoder crash bug present in v0.9.7
      related to the clamping of motion vectors in SPLITMV blocks. This
      behavior could be triggered by corrupt input or by starting
      decoding from a P-frame.


2011-08-15 v0.9.7-p1 "Cayuga" patch 1
  This is an incremental bugfix release against Cayuga. All users of that
  release are strongly encouraged to upgrade.

    - Fix potential OOB reads (cdae03a)

          An unbounded out of bounds read was discovered when the
          decoder was requested to perform error concealment (new in
          Cayuga) given a frame with corrupt partition sizes.

          A bounded out of bounds read was discovered affecting all
          versions of libvpx. Given an multipartition input frame that
          is truncated between the mode/mv partition and the first
          residiual paritition (in the block of partition offsets), up
          to 3 extra bytes could have been read from the source buffer.
          The code will not take any action regardless of the contents
          of these undefined bytes, as the truncated buffer is detected
          immediately following the read based on the calculated
          starting position of the coefficient partition.

    - Fix potential error concealment crash when the very first frame
      is missing or corrupt (a609be5)

    - Fix significant artifacts in error concealment (a4c2211, 99d870a)

    - Revert 1-pass CBR rate control changes (e961317)
      Further testing showed this change produced undesirable visual
      artifacts, rolling back for now.