[SCM] libav/experimental: Use a list to track which fragments coded in this frame still have outstanding coefficients yet to be decoded from the bitstream. Once a fragment reaches end-of-block, remove it from this new list. This change makes the VP3/Theora entropy decode process dramatically faster due to not having to iterate incessantly over fragments which have already been fully decoded.
siretart at users.alioth.debian.org
siretart at users.alioth.debian.org
Sun Jun 30 16:55:20 UTC 2013
The following commit has been merged in the experimental branch:
commit 098523eb28df3a1cf4bddca088d80d5cbd2b9a1f
Author: Mike Melanson <mike at multimedia.cx>
Date: Wed Dec 2 02:30:15 2009 +0000
Use a list to track which fragments coded in this frame still have
outstanding coefficients yet to be decoded from the bitstream. Once a
fragment reaches end-of-block, remove it from this new list. This change
makes the VP3/Theora entropy decode process dramatically faster due to
not having to iterate incessantly over fragments which have already been
fully decoded.
Originally committed as revision 20698 to svn://svn.ffmpeg.org/ffmpeg/trunk
diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c
index 60b84f0..292f010 100644
--- a/libavcodec/vp3.c
+++ b/libavcodec/vp3.c
@@ -179,6 +179,14 @@ typedef struct Vp3DecodeContext {
int coded_fragment_list_index;
int pixel_addresses_initialized;
+ /* track which fragments have already been decoded; called 'fast'
+ * because this data structure avoids having to iterate through every
+ * fragment in coded_fragment_list; once a fragment has been fully
+ * decoded, it is removed from this list */
+ int *fast_fragment_list;
+ int fragment_list_y_head;
+ int fragment_list_c_head;
+
VLC dc_vlc[16];
VLC ac_vlc_1[16];
VLC ac_vlc_2[16];
@@ -723,6 +731,25 @@ static int unpack_superblocks(Vp3DecodeContext *s, GetBitContext *gb)
/* end the list of coded C fragments */
s->last_coded_c_fragment = s->coded_fragment_list_index - 1;
+ for (i = 0; i < s->fragment_count - 1; i++) {
+ s->fast_fragment_list[i] = i + 1;
+ }
+ s->fast_fragment_list[s->fragment_count - 1] = -1;
+
+ if (s->last_coded_y_fragment == -1)
+ s->fragment_list_y_head = -1;
+ else {
+ s->fragment_list_y_head = s->first_coded_y_fragment;
+ s->fast_fragment_list[s->last_coded_y_fragment] = -1;
+ }
+
+ if (s->last_coded_c_fragment == -1)
+ s->fragment_list_c_head = -1;
+ else {
+ s->fragment_list_c_head = s->first_coded_c_fragment;
+ s->fast_fragment_list[s->last_coded_c_fragment] = -1;
+ }
+
return 0;
}
@@ -1029,7 +1056,7 @@ static int unpack_block_qpis(Vp3DecodeContext *s, GetBitContext *gb)
*/
static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
VLC *table, int coeff_index,
- int first_fragment, int last_fragment,
+ int y_plane,
int eob_run)
{
int i;
@@ -1038,6 +1065,10 @@ static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
DCTELEM coeff = 0;
Vp3Fragment *fragment;
int bits_to_get;
+ int next_fragment;
+ int previous_fragment;
+ int fragment_num;
+ int *list_head;
/* local references to structure members to avoid repeated deferences */
uint8_t *perm= s->scantable.permutated;
@@ -1045,20 +1076,26 @@ static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
Vp3Fragment *all_fragments = s->all_fragments;
uint8_t *coeff_counts = s->coeff_counts;
VLC_TYPE (*vlc_table)[2] = table->table;
+ int *fast_fragment_list = s->fast_fragment_list;
- if ((first_fragment >= s->fragment_count) ||
- (last_fragment >= s->fragment_count)) {
-
- av_log(s->avctx, AV_LOG_ERROR, " vp3:unpack_vlcs(): bad fragment number (%d -> %d ?)\n",
- first_fragment, last_fragment);
- return 0;
+ if (y_plane) {
+ next_fragment = s->fragment_list_y_head;
+ list_head = &s->fragment_list_y_head;
+ } else {
+ next_fragment = s->fragment_list_c_head;
+ list_head = &s->fragment_list_c_head;
}
- for (i = first_fragment; i <= last_fragment; i++) {
- int fragment_num = coded_fragment_list[i];
+ i = next_fragment;
+ previous_fragment = -1; /* this indicates that the previous fragment is actually the list head */
+ while (i != -1) {
+ fragment_num = coded_fragment_list[i];
- if (coeff_counts[fragment_num] > coeff_index)
+ if (coeff_counts[fragment_num] > coeff_index) {
+ previous_fragment = i;
+ i = fast_fragment_list[i];
continue;
+ }
fragment = &all_fragments[fragment_num];
if (!eob_run) {
@@ -1091,10 +1128,20 @@ static int unpack_vlcs(Vp3DecodeContext *s, GetBitContext *gb,
s->next_coeff->next=NULL;
fragment->next_coeff= s->next_coeff++;
}
+ /* previous fragment is now this fragment */
+ previous_fragment = i;
} else {
coeff_counts[fragment_num] |= 128;
eob_run--;
+ /* remove this fragment from the list */
+ if (previous_fragment != -1)
+ fast_fragment_list[previous_fragment] = fast_fragment_list[i];
+ else
+ *list_head = fast_fragment_list[i];
+ /* previous fragment remains unchanged */
}
+
+ i = fast_fragment_list[i];
}
return eob_run;
@@ -1123,14 +1170,14 @@ static int unpack_dct_coeffs(Vp3DecodeContext *s, GetBitContext *gb)
/* unpack the Y plane DC coefficients */
residual_eob_run = unpack_vlcs(s, gb, &s->dc_vlc[dc_y_table], 0,
- s->first_coded_y_fragment, s->last_coded_y_fragment, residual_eob_run);
+ 1, residual_eob_run);
/* reverse prediction of the Y-plane DC coefficients */
reverse_dc_prediction(s, 0, s->fragment_width, s->fragment_height);
/* unpack the C plane DC coefficients */
residual_eob_run = unpack_vlcs(s, gb, &s->dc_vlc[dc_c_table], 0,
- s->first_coded_c_fragment, s->last_coded_c_fragment, residual_eob_run);
+ 0, residual_eob_run);
/* reverse prediction of the C-plane DC coefficients */
if (!(s->avctx->flags & CODEC_FLAG_GRAY))
@@ -1148,37 +1195,37 @@ static int unpack_dct_coeffs(Vp3DecodeContext *s, GetBitContext *gb)
/* unpack the group 1 AC coefficients (coeffs 1-5) */
for (i = 1; i <= 5; i++) {
residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_1[ac_y_table], i,
- s->first_coded_y_fragment, s->last_coded_y_fragment, residual_eob_run);
+ 1, residual_eob_run);
residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_1[ac_c_table], i,
- s->first_coded_c_fragment, s->last_coded_c_fragment, residual_eob_run);
+ 0, residual_eob_run);
}
/* unpack the group 2 AC coefficients (coeffs 6-14) */
for (i = 6; i <= 14; i++) {
residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_2[ac_y_table], i,
- s->first_coded_y_fragment, s->last_coded_y_fragment, residual_eob_run);
+ 1, residual_eob_run);
residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_2[ac_c_table], i,
- s->first_coded_c_fragment, s->last_coded_c_fragment, residual_eob_run);
+ 0, residual_eob_run);
}
/* unpack the group 3 AC coefficients (coeffs 15-27) */
for (i = 15; i <= 27; i++) {
residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_3[ac_y_table], i,
- s->first_coded_y_fragment, s->last_coded_y_fragment, residual_eob_run);
+ 1, residual_eob_run);
residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_3[ac_c_table], i,
- s->first_coded_c_fragment, s->last_coded_c_fragment, residual_eob_run);
+ 0, residual_eob_run);
}
/* unpack the group 4 AC coefficients (coeffs 28-63) */
for (i = 28; i <= 63; i++) {
residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_4[ac_y_table], i,
- s->first_coded_y_fragment, s->last_coded_y_fragment, residual_eob_run);
+ 1, residual_eob_run);
residual_eob_run = unpack_vlcs(s, gb, &s->ac_vlc_4[ac_c_table], i,
- s->first_coded_c_fragment, s->last_coded_c_fragment, residual_eob_run);
+ 0, residual_eob_run);
}
return 0;
@@ -1756,9 +1803,10 @@ static av_cold int vp3_decode_init(AVCodecContext *avctx)
s->coeff_counts = av_malloc(s->fragment_count * sizeof(*s->coeff_counts));
s->coeffs = av_malloc(s->fragment_count * sizeof(Coeff) * 65);
s->coded_fragment_list = av_malloc(s->fragment_count * sizeof(int));
+ s->fast_fragment_list = av_malloc(s->fragment_count * sizeof(int));
s->pixel_addresses_initialized = 0;
if (!s->superblock_coding || !s->all_fragments || !s->coeff_counts ||
- !s->coeffs || !s->coded_fragment_list) {
+ !s->coeffs || !s->coded_fragment_list || !s->fast_fragment_list) {
vp3_decode_end(avctx);
return -1;
}
@@ -2057,6 +2105,7 @@ static av_cold int vp3_decode_end(AVCodecContext *avctx)
av_free(s->coeff_counts);
av_free(s->coeffs);
av_free(s->coded_fragment_list);
+ av_free(s->fast_fragment_list);
av_free(s->superblock_fragments);
av_free(s->superblock_macroblocks);
av_free(s->macroblock_fragments);
--
Libav/FFmpeg packaging
More information about the pkg-multimedia-commits
mailing list