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Incorrect bit allocation in forced KF groups.

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The old 2 pass code estimated error distribution when coding a
forced (by interval) key frame. The result of this was that in some
cases, when allocating bits at the GF group level within a KF
group there was either a glut of bits or starvation of bits at the end
of the KF group.

Added code to rescan and get the correct data once the position of
a forced key frame has been determined.

Change-Id: I0c811675ef3f9e4109d14bd049d7641682ffcf11
This commit is contained in:
Paul Wilkins 2011-01-25 12:29:06 +00:00
parent d3e9409bb0
commit 336aa0b7da
1 changed files with 27 additions and 4 deletions
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31
vp8/encoder/firstpass.c
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@ -2423,12 +2423,35 @@ void vp8_find_next_key_frame(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
if (cpi->oxcf.auto_key
&& cpi->frames_to_key > (int)cpi->key_frame_frequency )
{
int current_pos = cpi->stats_in;
FIRSTPASS_STATS tmp_frame;
cpi->frames_to_key /= 2;
// Estimate corrected kf group error
kf_group_err /= 2.0;
kf_group_intra_err /= 2.0;
kf_group_coded_err /= 2.0;
// Copy first frame details
vpx_memcpy(&tmp_frame, &first_frame, sizeof(first_frame));
// Reset to the start of the group
reset_fpf_position(cpi, start_position);
kf_group_err = 0;
kf_group_intra_err = 0;
kf_group_coded_err = 0;
// Rescan to get the correct error data for the forced kf group
for( i = 0; i < cpi->frames_to_key; i++ )
{
// Accumulate kf group errors
kf_group_err += calculate_modified_err(cpi, &tmp_frame);
kf_group_intra_err += tmp_frame.intra_error;
kf_group_coded_err += tmp_frame.coded_error;
// Load a the next frame's stats
vp8_input_stats(cpi, &tmp_frame);
}
// Reset to the start of the group
reset_fpf_position(cpi, current_pos);
cpi->next_key_frame_forced = TRUE;
}