AOM/CHANGELOG

2023-11-17 v3.7.1
  This release includes several bug fixes. This release is ABI
  compatible with the last release. See
  https://aomedia.googlesource.com/aom/+log/v3.7.0..v3.7.1 for all the
  commits in this release.

  - Bug Fixes
    * aomedia:3349: heap overflow when increasing resolution
    * aomedia:3478: GCC 12.2.0 emits a -Wstringop-overflow warning on
      aom/av1/encoder/motion_search_facade.c
    * aomedia:3489: Detect encoder and image high bit depth mismatch
    * aomedia:3491: heap-buffer-overflow on frame size change
    * b/303023614:  Segfault at encoding time for high bit depth images

2023-08-10 v3.7.0
  This release includes new codec interfaces, compression efficiency and
  perceptual improvements, speedup and memory optimizations and many bug fixes.
  This release is ABI compatible with the last release.

  - New Features
    * New codec controls:
      * AV1E_SET_QUANTIZER_ONE_PASS: Set quantizer for each frame.
      * AV1E_ENABLE_RATE_GUIDE_DELTAQ: enable the rate distribution guided delta
        quantization in all intra mode. The "enable-rate-guide-deltaq" option is
        added for this control.
      * AV1E_SET_RATE_DISTRIBUTION_INFO: set the input file for rate
        distribution used in all intra mode. The "rate-distribution-info" option
        is added for this control.
      * AV1E_GET_LUMA_CDEF_STRENGTH
      * AV1E_SET_BITRATE_ONE_PASS_CBR
    * AOM_SCALING_MODE is extended to include 2/3 and 1/3 scaling.
    * aom_tune_metric is extended to include AOM_TUNE_VMAF_SALIENCY_MAP.
      The "tune" option is extended to include "vmaf_saliency_map".
    * SVC example encoder svc_encoder_rtc is able to use the rate control
      library.
    * Loopfilter level and CDEF filter level is supported by RTC rate control
      library.
    * New speed (--cpu-used) 11, intended for RTC screen sharing, added for
      faster encoding with ~3% bdrate loss with 16% IC (instruction count)
      speedup compared to speed 10.

  - Compression Efficiency Improvements
    * Improved VoD encoding performance
      * 0.1-0.6% BDrate gains for encoding speeds 2 to 6
      * Rate control accuracy improvement in VBR mode
    * RTC encoding improvements
      * Screen content mode: 10-19% BDrate gains for speeds 6 - 10
      * Temporal layers video mode, for speed 10:
        * 2 temporal layers on low resolutions: 13-15% BDrate gain
        * 3 temporal layers on VGA/HD: 3-4% BDrate gain

  - Perceptual Quality Improvements
    * Fixed multiple block and color artifacts for RTC screen content by
      * Incorporating color into RD cost for IDTX
      * Reducing thresholds for palette mode in non RD mode
      * Allowing more palette mode testing
    * Improved color sensitivity for altref in non-RD mode.
    * Reduced video flickering for temporal layer encoding.

  - Speedup and Memory Optimizations
    * Speed up the VoD encoder
      * 2-5% for encoding speed 2 to 4
      * 9-15% for encoding speed 5 to 6
      * ARM
        * Standard bitdepth
          * speed 5: +31%
          * speed 4: +2%
          * speed 3: +9%
          * speed 2: +157%
        * High bitdepth
          * speed 5: +85%
    * RTC speedups
      * Screen content mode
        * 15% IC speedup for speeds 6-8
        * ARM: 7% for speed 9, 3% for speed 10
      * Temporal layers video mode
        * 7% speedup for 3 temporal layers on VGA/HD, for speed 10
      * Single layer video
        * x86: 2% IC speedup for speeds 7-10
        * ARM: 2-4% speedup across speeds 5-10

  - Other improvements
    * VoD: Major improvements to global motion estimation, now enabled up to
      speed 4
    * RTC
      * Fixes to make lossless coding work.
      * Fixes to make frame dropper (--drop_frames) work for single and temporal
        layers.
      * Improvements to RPS (reference picture selection) recovery frames.
      * Improvements to rate control for temporal layers.
    * libwebm is updated to libwebm-1.0.0.29-9-g1930e3c

  - Bug Fixes
    * aomedia:3261 Assertion failed when encoding av1 with film grain and
      '--monochrome' flag
    * aomedia:3276 ensure all allocations are checked (partial fix)
    * aomedia:3451 The libaom library calls exit()
    * aomedia:3450 enable -Wshadow for C++ sources
    * aomedia:3449 Test Seg Faults After
      b459af3e345be402db052a143fcc5383d4b74cbd
    * aomedia:3416 prune unused symbols / restrict symbol visibility
    * aomedia:3443 Jenkins failure:
      UninstantiatedParameterizedTestSuite<EstimateNoiseTest>
    * aomedia:3434 realtime failures with CONFIG_BITSTREAM_DEBUG=1
    * aomedia:3433 DeltaqModeTest crash w/row_mt=0
    * aomedia:3429 Encoder crash when turn on both ExternalResize and
      g_threads > 2
    * aomedia:3438 Build failure with
      `-DSANITIZE=address -DBUILD_SHARED_LIBS=ON` when using clang.
    * aomedia:3435 Block artifacts when scrolling with AV1 in screen sharing
      scenarios
    * aomedia:3170 vmaf tune presets produce extreme glitches in one scene
    * aomedia:3401 Building shared libaom with MSVC results in a race condition
      with the export library
    * aomedia:3420 Floating point exception in av1_tpl_get_frame_importance()
    * aomedia:3424 heap-buffer-overflow in ScaleFilterCols_16_C() (SIGABRT)
    * aomedia:3417 examples/svc_encoder_rtc.c is using internal macros and
      functions
    * aomedia:3372 SEGV in assign_frame_buffer_p av1_common_int.h
    * aomedia:3130 'cpu-features.h' file not found on Android NDK 22
    * aomedia:3415 Encoder/decoder mismatch for svc_encoder_rtc running
      1 SL 3 TL
    * aomedia:3412 Lossless Mode Fails Loopback Bit Test
    * aomedia:3409 The use of AV1_VAR_OFFS in av1/encoder/var_based_part.c is
      incorrect for high bit depths
    * aomedia:3403 test_libaom fails with error message
      "feenableexcept() failed" on Linux arm
    * aomedia:3370 Random color block at fast motion area
    * aomedia:3393 Assertion failure in av1_convolve_2d_sr_c()
    * aomedia:3392 Strong artifacting for high bit-depth real-time
    * aomedia:3376 aomenc --threads=10 --deltaq-mode=3 crashes after
      "Allintra: multi-threading of calculating differential contrast"
    * aomedia:3380 Crashes and ASan and TSan errors in deltaq-mode=3
      multithreading code
    * chromium:1410766 heap-buffer-overflow in aom_yv12_copy_v_c
    * Cannot set level via AV1E_SET_TARGET_SEQ_LEVEL_IDX
    * Encoding failure due to the use of loop restoration with unintended use of
      lossless mode.
    * Signed integer overflow in scan_past_frames
    * Signed integer overflow in update_a_sep_sym
    * Flickering in AV1 1440p/2160p HDR transcodes
    * Fixed artifacts with screen share at encoder speed 10
    * Fixed prediction setup for IDTX

2023-05-08 v3.6.1
  This release includes several bug fixes. This release is ABI
  compatible with the last release. See
  https://aomedia.googlesource.com/aom/+log/v3.6.0..v3.6.1 for all the
  commits in this release.

  - Bug Fixes
    * aomedia:2871: Guard the support of the 7.x and 8.x levels for AV1
      under the CONFIG_CWG_C013 config flag, and only output the 7.x and
      8.x levels when explicitly requested.
    * aomedia:3382: Choose sb_size by ppi instead of svc.
    * aomedia:3384: Fix fullpel search limits.
    * aomedia:3388: Replace left shift of xq_active by multiplication.
    * aomedia:3389: Fix MV clamping in av1_mv_pred.
    * aomedia:3390: set_ld_layer_depth: cap max_layer_depth to
      MAX_ARF_LAYERS.
    * aomedia:3418: Fix MV clamping in av1_int_pro_motion_estimation.
    * aomedia:3429: Move lpf thread data init to lpf_pipeline_mt_init().
    * b:266719111: Fix undefined behavior in Arm Neon code.
    * b:269840681: nonrd_opt: align scan tables.
    * rtc: Fix is_key_frame setting in variance partition.
    * Build: Fix build with clang-cl and Visual Studio.
    * Build: Fix module definition file for MinGW/MSYS.

2023-02-03 v3.6.0
  This release includes compression efficiency and perceptual quality
  improvements, speedup and memory optimizations, and some new features.
  This release is ABI compatible with the last release.

  - New Features
    * New values 20-27 (corresponding to levels 7.0-7.3 and 8.0-8.3) for
      the encoder control AV1E_SET_TARGET_SEQ_LEVEL_IDX (note that the
      proposal to add the new levels are still in draft status). The
      original special value 24 (keep level stats only for level
      monitoring) is renumbered as 32.
    * New encoder control AV1E_SET_SKIP_POSTPROC_FILTERING to skip the
      application of post-processing filters on reconstructed frame in
      all intra mode.
    * New encoder option "kf-max-pyr-height": Maximum height of pyramid
      structure used for the GOP starting with a key frame (-1 to 5).
    * Make SVC work for screen content.
    * Rate control improvements to reduce frame-size spikes for screen
      content coding.
    * RISC-V architecture support with gcc toolchain.

  - Compression Efficiency Improvements
    * Peak compression efficiency in VOD setting is improved by 1%.
    * 0.7% - 2.2% RTC encoding BDrate gains for real time speed 8 to 10.
    * 15% RTC encoding BDrate gains for screen content speed 10.

  - Perceptual Quality Improvements
    * Resolved a visual quality issue that was reported for high
      resolution clips (2K) for speed 4 and above in VOD use case.
    * Visual quality improvements to screen content coding.
    * Quality improvements to temporal layer RTC coding.

  - Speedup and Memory Optimizations
    * RTC single-thread encoder speedup:
      o ~6% instruction count reduction for speed 5 and 6.
      o ~15% instruction count reduction for speed 7.
      o ~10% instruction count reduction for speed 8 to 10 (>=360p
        resolutions).
    * RTC multi-thread encoder speedup (beyond single-thread speedup):
      o 5-8% encode time reduction for speed 7 to 10.
    * RTC screen-content encoder speedup:
      o 11% instruction count reduction for speed 9 and 10 (>=720p
        resolutions).
    * ~5% reduction in heap memory requirements for RTC, speed 6 to 10.
    * AVIF:
      o 4-5% speedup for speed 9 in still-picture encoding mode.
      o 3-4% heap memory reduction in still-picture encoding mode for
        360p-720p resolutions with multiple threads.

  - Bug Fixes
    * Added a workaround for an AV1 specification bug which makes
      TRANSLATION type global motion models unusable.
    * Fixed AddressSanitizer global-buffer-overflow errors in
      av1/encoder/arm/neon/av1_fwd_txfm2d_neon.c.
    * Fixed AddressSanitizer heap-buffer-overflow error in
      av1_wiener_convolve_add_src_neon().
    * chromium:1393384 Avoid scene detection on spatial resize.
    * aomedia:3308 Remove color artifacts under high motion.
    * aomedia:3310 Avoid out of memory failures with Visual Studio 2017,
      2019, and 2022 for Win32 x86 builds.
    * aomedia:3346 Make SVC work properly for screen content.
    * aomedia:3348 Fix a bug where an uninitialized search_site is used.
    * aomedia:3365 Work around what seems like a Visual Studio 2022
      compiler optimization bug.
    * aomedia:3369 Incorrect PSNR values reported by libaom for 12-bit
      encode.

2022-08-31 v3.5.0
  This release is ABI compatible with the last one, including speedup and memory
  optimizations, and new APIs and features.

  - New Features
    * Support for frame parallel encode for larger number of threads. --fp-mt
      flag is available for all build configurations.
    * New codec control AV1E_GET_NUM_OPERATING_POINTS

  - Speedup and Memory Optimizations
    * Speed-up multithreaded encoding for good quality mode for larger number of
      threads through frame parallel encoding:
      o 30-34% encode time reduction for 1080p, 16 threads, 1x1 tile
        configuration (tile_rows x tile_columns)
      o 18-28% encode time reduction for 1080p, 16 threads, 2x4 tile
        configuration
      o 18-20% encode time reduction for 2160p, 32 threads, 2x4 tile
        configuration
    * 16-20% speed-up for speed=6 to 8 in still-picture encoding mode
    * 5-6% heap memory reduction for speed=6 to 10 in real-time encoding mode
    * Improvements to the speed for speed=7, 8 in real-time encoding mode
    * Improvements to the speed for speed=9, 10 in real-time screen encoding
      mode
    * Optimizations to improve multi-thread efficiency in real-time encoding
      mode
    * 10-15% speed up for SVC with temporal layers
    * SIMD optimizations:
      o Improve av1_quantize_fp_32x32_neon() 1.05x to 1.24x faster
      o Add aom_highbd_quantize_b{,_32x32,_64x64}_adaptive_neon() 3.15x to 5.6x
        faster than "C"
      o Improve av1_quantize_fp_64x64_neon() 1.17x to 1.66x faster
      o Add aom_quantize_b_avx2() 1.4x to 1.7x faster than aom_quantize_b_avx()
      o Add aom_quantize_b_32x32_avx2() 1.4x to 2.3x faster than
        aom_quantize_b_32x32_avx()
      o Add aom_quantize_b_64x64_avx2() 2.0x to 2.4x faster than
        aom_quantize_b_64x64_ssse3()
      o Add aom_highbd_quantize_b_32x32_avx2() 9.0x to 10.5x faster than
        aom_highbd_quantize_b_32x32_c()
      o Add aom_highbd_quantize_b_64x64_avx2() 7.3x to 9.7x faster than
        aom_highbd_quantize_b_64x64_c()
      o Improve aom_highbd_quantize_b_avx2() 1.07x to 1.20x faster
      o Improve av1_quantize_fp_avx2() 1.13x to 1.49x faster
      o Improve av1_quantize_fp_32x32_avx2() 1.07x to 1.54x faster
      o Improve av1_quantize_fp_64x64_avx2()  1.03x to 1.25x faster
      o Improve av1_quantize_lp_avx2() 1.07x to 1.16x faster

  - Bug fixes including but not limited to
    * aomedia:3206 Assert that skip_width > 0 for deconvolve function
    * aomedia:3278 row_mt enc: Delay top-right sync when intraBC is enabled
    * aomedia:3282 blend_a64_*_neon: fix bus error in armv7
    * aomedia:3283 FRAME_PARALLEL: Propagate border size to all cpis
    * aomedia:3283 RESIZE_MODE: Fix incorrect strides being used for motion
      search
    * aomedia:3286 rtc-svc: Fix to dynamic_enable spatial layers
    * aomedia:3289 rtc-screen: Fix to skipping inter-mode test in nonrd
    * aomedia:3289 rtc-screen: Fix for skip newmv on flat blocks
    * aomedia:3299 Fix build failure with CONFIG_TUNE_VMAF=1
    * aomedia:3296 Fix the conflict --enable-tx-size-search=0 with nonrd mode
      --enable-tx-size-search will be ignored in non-rd pick mode
    * aomedia:3304 Fix off-by-one error of max w/h in validate_config
    * aomedia:3306 Do not use pthread_setname_np on GNU/Hurd
    * aomedia:3325 row-multithreading produces invalid bitstream in some cases
    * chromium:1346938, chromium:1338114
    * compiler_flags.cmake: fix flag detection w/cmake 3.17-3.18.2
    * tools/*.py: update to python3
    * aom_configure.cmake: detect PIE and set CONFIG_PIC
    * test/simd_cmp_impl: use explicit types w/CompareSimd*
    * rtc: Fix to disable segm for aq-mode=3
    * rtc: Fix to color_sensitivity in variance partition
    * rtc-screen: Fix bsize in model rd computation for intra chroma
    * Fixes to ensure the correct behavior of the encoder algorithms (like
      segmentation, computation of statistics, etc.)

2022-06-17 v3.4.0
  This release includes compression efficiency and perceptual quality
  improvements, speedup and memory optimizations, and some new features.
  There are no ABI or API breaking changes in this release.

  - New Features
    * New --dist-metric flag with "qm-psnr" value to use quantization
      matrices in the distortion computation for RD search. The default
      value is "psnr".
    * New command line option "--auto-intra-tools-off=1" to make
      all-intra encoding faster for high bit rate under
      "--deltaq-mode=3" mode.
    * New rate control library aom_av1_rc for real-time hardware
      encoders. Supports CBR for both one spatial layer and SVC.
    * New image format AOM_IMG_FMT_NV12 can be used as input to the
      encoder. The presence of AOM_IMG_FMT_NV12 can be detected at
      compile time by checking if the macro AOM_HAVE_IMG_FMT_NV12 is
      defined.
    * New codec controls for the encoder:
      o AV1E_SET_AUTO_INTRA_TOOLS_OFF. Only in effect if
        --deltaq-mode=3.
      o AV1E_SET_RTC_EXTERNAL_RC
      o AV1E_SET_FP_MT. Only supported if libaom is built with
        -DCONFIG_FRAME_PARALLEL_ENCODE=1.
      o AV1E_GET_TARGET_SEQ_LEVEL_IDX
    * New key-value pairs for the key-value API:
      o --auto-intra-tools-off=0 (default) or 1. Only in effect if
        --deltaq-mode=3.
      o --strict-level-conformance=0 (default) or 1
      o --fp-mt=0 (default) or 1. Only supported if libaom is built
        with -DCONFIG_FRAME_PARALLEL_ENCODE=1.
    * New aomenc options (not supported by the key-value API):
      o --nv12

  - Compression Efficiency Improvements
    * Correctly calculate SSE for high bitdepth in skip mode, 0.2% to
      0.6% coding gain.
    * RTC at speed 9/10: BD-rate gain of ~4/5%
    * RTC screen content coding: many improvements for real-time screen
      at speed 10 (quality, speedup, and rate control), up to high
      resolutions (1080p).
    * RTC-SVC: fixes to make intra-only frames work for spatial layers.
    * RTC-SVC: quality improvements for temporal layers.
    * AV1 RT: A new passive rate control strategy for screen content, an
      average of 7.5% coding gain, with some clips of 20+%. The feature
      is turned off by default due to higher bit rate variation.

  - Perceptual Quality Improvements
    * RTC: Visual quality improvements for high speeds (9/10)
    * Improvements in coding quality for all intra mode

  - Speedup and Memory Optimizations
    * ~10% speedup in good quality mode encoding.
    * ~7% heap memory reduction in good quality encoding mode for speed
      5 and 6.
    * Ongoing improvements to intra-frame encoding performance on Arm
    * Faster encoding speed for "--deltaq-mode=3" mode.
    * ~10% speedup for speed 5/6, ~15% speedup for speed 7/8, and
      ~10% speedup for speed 9/10 in real time encoding mode
    * ~20% heap memory reduction in still-picture encoding mode for
      360p-720p resolutions with multiple threads
    * ~13% speedup for speed 6 and ~12% speedup for speed 9 in
      still-picture encoding mode.
    * Optimizations to improve multi-thread efficiency for still-picture
      encoding mode.

  - Bug Fixes
    * b/204460717: README.md: replace master with main
    * b/210677928: libaom disable_order is surprising for
      max_reference_frames=3
    * b/222461449: -DCONFIG_TUNE_BUTTERAUGLI=1 broken
    * b/227207606: write_greyscale writes incorrect chroma in highbd
      mode
    * b/229955363: Integer-overflow in linsolve_wiener
    * https://crbug.com/aomedia/2032
    * https://crbug.com/aomedia/2397
    * https://crbug.com/aomedia/2563
    * https://crbug.com/aomedia/2815
    * https://crbug.com/aomedia/3009
    * https://crbug.com/aomedia/3018
    * https://crbug.com/aomedia/3045
    * https://crbug.com/aomedia/3101
    * https://crbug.com/aomedia/3130
    * https://crbug.com/aomedia/3173
    * https://crbug.com/aomedia/3184
    * https://crbug.com/aomedia/3187
    * https://crbug.com/aomedia/3190
    * https://crbug.com/aomedia/3195
    * https://crbug.com/aomedia/3197
    * https://crbug.com/aomedia/3201
    * https://crbug.com/aomedia/3202
    * https://crbug.com/aomedia/3204
    * https://crbug.com/aomedia/3205
    * https://crbug.com/aomedia/3207
    * https://crbug.com/aomedia/3208
    * https://crbug.com/aomedia/3209
    * https://crbug.com/aomedia/3213
    * https://crbug.com/aomedia/3214
    * https://crbug.com/aomedia/3219
    * https://crbug.com/aomedia/3222
    * https://crbug.com/aomedia/3223
    * https://crbug.com/aomedia/3225
    * https://crbug.com/aomedia/3226
    * https://crbug.com/aomedia/3228
    * https://crbug.com/aomedia/3232
    * https://crbug.com/aomedia/3236
    * https://crbug.com/aomedia/3237
    * https://crbug.com/aomedia/3238
    * https://crbug.com/aomedia/3240
    * https://crbug.com/aomedia/3243
    * https://crbug.com/aomedia/3244
    * https://crbug.com/aomedia/3246
    * https://crbug.com/aomedia/3248
    * https://crbug.com/aomedia/3250
    * https://crbug.com/aomedia/3251
    * https://crbug.com/aomedia/3252
    * https://crbug.com/aomedia/3255
    * https://crbug.com/aomedia/3257
    * https://crbug.com/aomedia/3259
    * https://crbug.com/aomedia/3260
    * https://crbug.com/aomedia/3267
    * https://crbug.com/aomedia/3268
    * https://crbug.com/aomedia/3269
    * https://crbug.com/aomedia/3276
    * https://crbug.com/aomedia/3278
    * https://crbug.com/chromium/1290068
    * https://crbug.com/chromium/1303237
    * https://crbug.com/chromium/1304990
    * https://crbug.com/chromium/1321141
    * https://crbug.com/chromium/1321388
    * https://crbug.com/oss-fuzz/44846
    * https://crbug.com/oss-fuzz/44856
    * https://crbug.com/oss-fuzz/44862
    * https://crbug.com/oss-fuzz/44904
    * https://crbug.com/oss-fuzz/45056

2022-01-28 v3.3.0
  This release includes compression efficiency and perceptual quality
  improvements, speedup and memory optimizations, some new features, and
  several bug fixes.

  - New Features
    * AV1 RT: Introducing CDEF search level 5
    * Changed real time speed 4 to behave the same as real time speed 5
    * Add --deltaq-strength
    * rtc: Allow scene-change and overshoot detection for svc
    * rtc: Intra-only frame for svc
    * AV1 RT: Option 2 for codec control AV1E_SET_ENABLE_CDEF to disable
      CDEF on non-ref frames
    * New codec controls AV1E_SET_LOOPFILTER_CONTROL and
      AOME_GET_LOOPFILTER_LEVEL
    * Improvements to three pass encoding

  - Compression Efficiency Improvements
    * Overall compression gains: 0.6%

  - Perceptual Quality Improvements
    * Improves the perceptual quality of high QP encoding for delta-q mode 4
    * Auto select noise synthesis level for all intra

  - Speedup and Memory Optimizations
    * Added many SSE2 optimizations.
    * Good quality 2-pass encoder speedups:
      o Speed 2: 9%
      o Speed 3: 12.5%
      o Speed 4: 8%
      o Speed 5: 3%
      o Speed 6: 4%
    * Real time mode encoder speedups:
      o Speed 5: 2.6% BDRate gain, 4% speedup
      o Speed 6: 3.5% BDRate gain, 4% speedup
      o Speed 9: 1% BDRate gain, 3% speedup
      o Speed 10: 3% BDRate gain, neutral speedup
    * All intra encoding speedups (AVIF):
      o Single thread - speed 6: 8%
      o Single thread - speed 9: 15%
      o Multi thread(8) - speed 6: 14%
      o Multi thread(8) - speed 9: 34%

  - Bug Fixes
    * Issue 3163: Segmentation fault when using --enable-keyframe-filtering=2
    * Issue 2436: Integer overflow in av1_warp_affine_c()
    * Issue 3226: armv7 build failure due to gcc-11
    * Issue 3195: Bug report on libaom (AddressSanitizer: heap-buffer-overflow)
    * Issue 3191: Bug report on libaom (AddressSanitizer: SEGV on unknown
      address)
    * Issue 3176: Some SSE2/SADx4AvgTest.* tests fail on Windows
    * Issue 3175: Some SSE2/SADSkipTest.* tests fail on Windows

2021-10-13 v3.2.0
  This release includes compression efficiency and perceptual quality
  improvements, speedup and memory optimizations, as well as some new
  features.

  - New Features
    * Introduced speeds 7, 8, and 9 for all intra mode.
    * Introduced speed 10 for real time mode.
    * Introduced an API that allows external partition decisions.
    * SVC: added support for compound prediction.
    * SVC: added support for fixed SVC modes.

  - Compression Efficiency Improvements
    * Intra-mode search improvement.
    * Improved real time (RT) mode BDrate savings by ~5% (RT speed 5)
      and ~12% (RT speed 6). The improvement was measured on the video
      conference set.
    * Improved real time mode for nonrd path (speed 7, 8, 9): BDrate
      gains of ~3-5%.
    * Rate control and RD adjustments based on ML research in VP9.
      Gains of ~0.5-1.0% for HD.

  - Perceptual Quality Improvements
    * Added a new mode --deltaq-mode=3 to improve perceptual quality
      based on a differential contrast model for still images.
    * Added a new mode --deltaq-mode=4 to improve perceptual quality
      based on user rated cq_level data set for still images.
    * Weighting of some intra mode and partition size choices to better
      manage and retain texture.

  - Speedup and Memory Optimizations
    * Further improved 2-pass good quality encoder speed:
      o Speed 2 speedup: 18%
      o Speed 3 speedup: 22%
      o Speed 4 speedup: 37%
      o Speed 5 speedup: 30%
      o Speed 6 speedup: 20%
    * Optimized the real time encoder (measured on the video conference
      set):
      o RT speed 5 speedup: 110%
      o RT speed 6 speedup: 77%

  - Bug Fixes
    * Issue 3069: Fix one-pass mode keyframe placement off-by-one error.
    * Issue 3156: Fix a bug in av1_quantize_lp AVX2 optimization.

2021-09-29 v3.1.3
  This release includes several bug fixes.

  - Bug fixes:
    The following four cmake changes should help the people building
    libaom using MSVC.
      1. exports: use CMAKE_SHARED_LIBRARY_PREFIX to determine lib name
         https://aomedia-review.googlesource.com/c/aom/+/142342
      2. aom_install: Install lib dlls to bindir
         https://aomedia-review.googlesource.com/c/aom/+/146546
      3. aom_install: use relpath for install
         https://aomedia-review.googlesource.com/c/aom/+/146550
      4. aom_install: don't exclude msvc from install
         https://aomedia-review.googlesource.com/c/aom/+/146547

    aom/aom_encoder.h: remove configure option reference
    https://aomedia-review.googlesource.com/c/aom/+/146743

    Issue 3113: Tests for detecting chroma subsampling in
    av1_copy_and_extend_frame() do not work when y_width or y_height is
    1

    Issue 3115: image2yuvconfig() should calculate uv_crop_width and
    uv_crop_height from y_crop_width and y_crop_height

    Issue 3140: rc_overshoot_pct is documented as having a range of
    0-1000, but is range checked against 0-100

    Issue 3147: Build failure on Apple M1 arm64

2021-07-20 v3.1.2
  This release includes several bug fixes.

  - Bug fixes:
    exports.cmake: use APPLE and WIN32 and use def for mingw-w64
    https://aomedia-review.googlesource.com/c/aom/+/139882

    Issue 2993: Incorrect spatial_id when decoding base layer of
    multi-layer stream

    Issue 3080: Chroma Resampling by Encoder on Y4M Inputs Files Tagged
    as C420mpeg2

    Issue 3081: Use of uninitialized value $version_extra in
    concatenation (.) or string at aom/build/cmake/version.pl line 88.

2021-06-08 v3.1.1
  This release includes several bug fixes.

  - Bug fixes:
    Issue 2965: Cherry-picked the following four commits for the
    tune=butteraugli mode.
      1. Add libjxl to pkg_config if enabled:
         https://aomedia-review.googlesource.com/c/aom/+/136044
      2. Declare set_mb_butteraugli_rdmult_scaling static:
         https://aomedia-review.googlesource.com/c/aom/+/134506
      3. Add color range detection in tune=butteraugli mode:
         https://aomedia-review.googlesource.com/c/aom/+/135521
      4. Enable tune=butteraugli in all-intra mode:
         https://aomedia-review.googlesource.com/c/aom/+/136082

    Issue 3021: Fix vmaf model initialization error when not set to
    tune=vmaf

    Issue 3050: Compilation fails with -DCONFIG_TUNE_VMAF=1

    Issue 3054: Consistent crash on near-static screen content, keyframe
    related

2021-05-03 v3.1.0
  This release adds an "all intra" mode to the encoder, which significantly
  speeds up the encoding of AVIF still images at speed 6.

  - Upgrading:
    All intra mode for encoding AVIF still images and AV1 all intra videos:
    AOM_USAGE_ALL_INTRA (2) can be passed as the 'usage' argument to
    aom_codec_enc_config_default().

    New encoder control IDs added:
      - AV1E_SET_ENABLE_DIAGONAL_INTRA: Enable diagonal (D45 to D203) intra
        prediction modes (0: false, 1: true (default)). Also available as
        "enable-diagonal-intra" for the aom_codec_set_option() function.

    New aom_tune_metric enum value: AOM_TUNE_BUTTERAUGLI. The new aomenc option
    --tune=butteraugli was added to optimize the encoder's perceptual quality by
    optimizing the Butteraugli metric. Install libjxl (JPEG XL) and then pass
    -DCONFIG_TUNE_BUTTERAUGLI=1 to the cmake command to enable it.

    Addition of support for libvmaf 2.x.

  - Enhancements:
    Heap memory consumption for encoding AVIF still images is significantly
    reduced.

  - Bug fixes:
    Issue 2601: third_party/libaom fails licensecheck

    Issue 2950: Conditional expression for rc->this_key_frame_forced is always
    true in find_next_key_frame()

    Issue 2988: "make install" installs the aom.h header twice

    Issue 2992: Incorrectly printing the temporal_id twice in dump_obu tool

    Issue 2998:

    Issue 2999:

    Issue 3000:

2021-02-24 v3.0.0
  This release includes compression efficiency improvement, speed improvement
  for realtime mode, as well as some new APIs.

  - Upgrading:
    Support for PSNR calculation based on stream bit-depth.

    New encoder control IDs added:
      - AV1E_SET_ENABLE_RECT_TX
      - AV1E_SET_VBR_CORPUS_COMPLEXITY_LAP
      - AV1E_GET_BASELINE_GF_INTERVAL
      - AV1E_SET_ENABLE_DNL_DENOISING

    New decoder control IDs added:
      - AOMD_GET_FWD_KF_PRESENT
      - AOMD_GET_FRAME_FLAGS
      - AOMD_GET_ALTREF_PRESENT
      - AOMD_GET_TILE_INFO
      - AOMD_GET_SCREEN_CONTENT_TOOLS_INFO
      - AOMD_GET_STILL_PICTURE
      - AOMD_GET_SB_SIZE
      - AOMD_GET_SHOW_EXISTING_FRAME_FLAG
      - AOMD_GET_S_FRAME_INFO

    New aom_tune_content enum value: AOM_CONTENT_FILM

    New aom_tune_metric enum value: AOM_TUNE_VMAF_NEG_MAX_GAIN

    Coefficient and mode update can be turned off via
    AV1E_SET_{COEFF/MODE}_COST_UPD_FREQ.

    New key & value API added, available with aom_codec_set_option() function.

    Scaling API expanded to include 1/4, 3/4 and 1/8.

  - Enhancements:
    Better multithreading performance with realtime mode.

    New speed 9 setting for faster realtime encoding.

    Smaller binary size with low bitdepth and realtime only build.

    Temporal denoiser and its optimizations on x86 and Neon.

    Optimizations for scaling.

    Faster encoding with speed settings 2 to 6 for good encoding mode.

    Improved documentation throughout the library, with function level
    documentation, tree view and support for the dot tool.

  - Bug fixes:
    Aside from those mentioned in v2.0.1 and v2.0.2, this release includes the
    following bug fixes:

    Issue 2940: Segfault when encoding with --use-16bit-internal and --limit > 1

    Issue 2941: Decoder mismatch with --rt --bit-depth=10 and --cpu-used=8

    Issue 2895: mingw-w64 i686 gcc fails to build

    Issue 2874: Separate ssse3 functions from sse2 file.

2021-02-09 v2.0.2
  This release includes several bug fixes.

  - Bug fixes:
    Issue 2643: Modify the assertion in temporal filter intrinsics.

    Issue 2648: Fix unit test ThreadTestLarge.EncoderResultTest/49
    assertion failure.

    Issue 2869: Add -Wimplicit-function-declaration as C flag only.

    Issue 2878: Avoid memset in the av1_filter_intra_predictor module
    functions.

    Issue 2903: Fix a typo bug in apply_temporal_filter_planewise.

    Call av1_setup_frame_size() when dropping a frame in the
    encode_frame_to_data_rate() function in av1/encoder/encoder.c.

2020-11-25 v2.0.1
  This release includes two bug fixes.

  - Bug fixes:
    Issue 2723: Fix crash in chroma_check() when generating a monochrome
    encoded stream in real-time mode.

    Issue 2833: Fix crash on some input when reduced still picture header is
    used in real-time mode and speed >=7.

2020-05-07 v2.0.0 "Applejack"
  First official release of libaom.
  This release includes new real-time mode and SVC support.

  - Upgrading:
    AOM_SET_POSTPROC, AOM_CODEC_CAP_POSTPROC and AOM_CODEC_USE_POSTPROC are
    removed.

    AOM_SET_DBG_* is removed.

    Multi-resolution encoding is removed.

    put_frame and put_slice callbacks are removed.

  - Enhancements:
    Full-sweep document update for codec controls.

2018-06-28 v1.0.0
  AOMedia Codec Workgroup Approved version 1.0

2016-04-07 v0.1.0 "AOMedia Codec 1"
  This release is the first Alliance for Open Media codec.