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Prevent parameters that can cause invalid ARF groups.

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Having a very low "lag_in_frames" value could cause the encoder to create
incorrect / corrupt ARF groups including displayed frames that update the
ARF buffer and false overlay frames that are coded at low rate but are not
actually overlays of a real ARF frame.

This is linked to a reported unit test "slow down" where the chosen parameters
(lag of 3 frames) gave rise to such "broken" ARF group(s).

See also BUG=webm:1454

Change-Id: If52d0236243ed5552537d1ea9ed3fed8c867232c
This commit is contained in:
paulwilkins 2017-08-16 13:34:49 +01:00
parent 48110d0f79
commit b814e2d898
2 changed files with 9 additions and 1 deletions
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3
vp9/encoder/vp9_encoder.h
View File

@ -867,9 +867,10 @@ static INLINE int denoise_svc(const struct VP9_COMP *const cpi) {
}
#endif
#define MIN_LOOKAHEAD_FOR_ARFS 4
static INLINE int is_altref_enabled(const VP9_COMP *const cpi) {
return !(cpi->oxcf.mode == REALTIME && cpi->oxcf.rc_mode == VPX_CBR) &&
cpi->oxcf.lag_in_frames > 0 &&
cpi->oxcf.lag_in_frames >= MIN_LOOKAHEAD_FOR_ARFS &&
(cpi->oxcf.enable_auto_arf &&
(!is_two_pass_svc(cpi) ||
cpi->oxcf.ss_enable_auto_arf[cpi->svc.spatial_layer_id]));

7
vp9/vp9_cx_iface.c
View File

@ -191,6 +191,13 @@ static vpx_codec_err_t validate_config(vpx_codec_alg_priv_t *ctx,
(MAX_LAG_BUFFERS - 1));
}
// For formation of valid ARF groups lag_in _frames should be 0 or greater
// than the max_gf_interval + 2
if (cfg->g_lag_in_frames > 0 && extra_cfg->max_gf_interval > 0 &&
cfg->g_lag_in_frames < extra_cfg->max_gf_interval + 2) {
ERROR("Set lag in frames to 0 (low delay) or >= (max-gf-interval + 2)");
}
if (cfg->rc_resize_allowed == 1) {
RANGE_CHECK(cfg, rc_scaled_width, 0, cfg->g_w);
RANGE_CHECK(cfg, rc_scaled_height, 0, cfg->g_h);