[FFmpeg-devel] [PATCH] dca: use EXT_AUDIO_ID field to determine core extensions
Anssi Hannula
anssi.hannula
Fri Feb 18 20:49:44 CET 2011
This avoids the core substream extensions scan when the EXT_AUDIO_ID
field indicates no extensions or only unsupported extensions. The scan
is done only if the value of EXT_AUDIO_ID is unknown or indicates a
present XCh extension which we can decode.
---
libavcodec/dca.c | 69 ++++++++++++++++++++++++++++++++++++++---------------
1 files changed, 49 insertions(+), 20 deletions(-)
diff --git a/libavcodec/dca.c b/libavcodec/dca.c
index bdbe018..9888b56 100644
--- a/libavcodec/dca.c
+++ b/libavcodec/dca.c
@@ -99,6 +99,21 @@ enum DCAExtensionMask {
DCA_EXT_EXSS_XLL = 0x200, ///< lossless extension in ExSS
};
+/* -1 are reserved or unknown */
+static const int dca_ext_audio_descr_mask[] = {
+ DCA_EXT_XCH,
+ -1,
+ DCA_EXT_X96,
+ DCA_EXT_XCH | DCA_EXT_X96,
+ -1,
+ -1,
+ DCA_EXT_XXCH,
+ -1,
+};
+
+/* extensions that reside in core substream */
+#define DCA_CORE_EXTS (DCA_EXT_XCH | DCA_EXT_XXCH | DCA_EXT_X96)
+
/* Tables for mapping dts channel configurations to libavcodec multichannel api.
* Some compromises have been made for special configurations. Most configurations
* are never used so complete accuracy is not needed.
@@ -327,14 +342,12 @@ typedef struct {
int current_subframe;
int current_subsubframe;
+ int core_ext_mask; ///< present extensions in the core substream
+
/* XCh extension information */
- int xch_present;
+ int xch_present; ///< XCh extension present and valid
int xch_base_channel; ///< index of first (only) channel containing XCH data
- /* Other detected extensions in the core substream */
- int xxch_present;
- int x96_present;
-
/* ExSS header parser */
int static_fields; ///< static fields present
int mix_metadata; ///< mixing metadata present
@@ -1508,12 +1521,9 @@ static int dca_exss_parse_asset_header(DCAContext *s)
if (!(extensions_mask & DCA_EXT_CORE))
av_log(s->avctx, AV_LOG_WARNING, "DTS core detection mismatch.\n");
- if (!!(extensions_mask & DCA_EXT_XCH) != s->xch_present)
- av_log(s->avctx, AV_LOG_WARNING, "DTS XCh detection mismatch.\n");
- if (!!(extensions_mask & DCA_EXT_XXCH) != s->xxch_present)
- av_log(s->avctx, AV_LOG_WARNING, "DTS XXCh detection mismatch.\n");
- if (!!(extensions_mask & DCA_EXT_X96) != s->x96_present)
- av_log(s->avctx, AV_LOG_WARNING, "DTS X96 detection mismatch.\n");
+ if ((extensions_mask & DCA_CORE_EXTS) != s->core_ext_mask)
+ av_log(s->avctx, AV_LOG_WARNING, "DTS extensions detection mismatch (%d, %d)\n",
+ extensions_mask & DCA_CORE_EXTS, s->core_ext_mask);
return 0;
}
@@ -1623,8 +1633,6 @@ static int dca_decode_frame(AVCodecContext * avctx,
s->xch_present = 0;
- s->x96_present = 0;
- s->xxch_present = 0;
s->dca_buffer_size = dca_convert_bitstream(buf, buf_size, s->dca_buffer,
DCA_MAX_FRAME_SIZE + DCA_MAX_EXSS_HEADER_SIZE);
@@ -1652,11 +1660,24 @@ static int dca_decode_frame(AVCodecContext * avctx,
/* record number of core channels incase less than max channels are requested */
num_core_channels = s->prim_channels;
- /* extensions start at 32-bit boundaries into bitstream */
- skip_bits_long(&s->gb, (-get_bits_count(&s->gb)) & 31);
+ if (s->ext_coding)
+ s->core_ext_mask = dca_ext_audio_descr_mask[s->ext_descr];
+ else
+ s->core_ext_mask = 0;
core_ss_end = FFMIN(s->frame_size, s->dca_buffer_size) * 8;
+ /* only scan for extensions if ext_descr was unknown or indicated a
+ * supported XCh extension */
+ if (s->core_ext_mask < 0 || s->core_ext_mask & DCA_EXT_XCH) {
+
+ /* if ext_descr was unknown, clear s->core_ext_mask so that the
+ * extensions scan can fill it up */
+ s->core_ext_mask = FFMAX(s->core_ext_mask, 0);
+
+ /* extensions start at 32-bit boundaries into bitstream */
+ skip_bits_long(&s->gb, (-get_bits_count(&s->gb)) & 31);
+
while(core_ss_end - get_bits_count(&s->gb) >= 32) {
uint32_t bits = get_bits_long(&s->gb, 32);
@@ -1675,7 +1696,7 @@ static int dca_decode_frame(AVCodecContext * avctx,
/* skip length-to-end-of-frame field for the moment */
skip_bits(&s->gb, 10);
- s->profile = FFMAX(s->profile, FF_PROFILE_DTS_ES);
+ s->core_ext_mask |= DCA_EXT_XCH;
/* extension amode should == 1, number of channels in extension */
/* AFAIK XCh is not used for more channels */
@@ -1699,8 +1720,7 @@ static int dca_decode_frame(AVCodecContext * avctx,
/* XXCh: extended channels */
/* usually found either in core or HD part in DTS-HD HRA streams,
* but not in DTS-ES which contains XCh extensions instead */
- s->xxch_present = 1;
- s->profile = FFMAX(s->profile, FF_PROFILE_DTS_ES);
+ s->core_ext_mask |= DCA_EXT_XXCH;
break;
case 0x1d95f262: {
@@ -1713,8 +1733,7 @@ static int dca_decode_frame(AVCodecContext * avctx,
av_log(avctx, AV_LOG_DEBUG, "FSIZE96 = %d bytes\n", fsize96);
av_log(avctx, AV_LOG_DEBUG, "REVNO = %d\n", get_bits(&s->gb, 4));
- s->x96_present = 1;
- s->profile = FFMAX(s->profile, FF_PROFILE_DTS_96_24);
+ s->core_ext_mask |= DCA_EXT_X96;
break;
}
}
@@ -1722,6 +1741,16 @@ static int dca_decode_frame(AVCodecContext * avctx,
skip_bits_long(&s->gb, (-get_bits_count(&s->gb)) & 31);
}
+ } else {
+ /* no supported extensions, skip the rest of the core substream */
+ skip_bits_long(&s->gb, core_ss_end - get_bits_count(&s->gb));
+ }
+
+ if (s->core_ext_mask & DCA_EXT_X96)
+ s->profile = FF_PROFILE_DTS_96_24;
+ else if (s->core_ext_mask & (DCA_EXT_XCH | DCA_EXT_XXCH))
+ s->profile = FF_PROFILE_DTS_ES;
+
/* check for ExSS (HD part) */
if (s->dca_buffer_size - s->frame_size > 32
&& get_bits_long(&s->gb, 32) == DCA_HD_MARKER)
--
1.7.3
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