Parse core frame size directly when searching for frame end instead of
using value extracted from previous frame.
Account for unused bits when calculating sync word distance for 14-bit
streams to avoid alias sync detection.
Parse EXSS frame size and skip over EXSS frame to avoid alias sync
detection.
---
libavcodec/dca_parser.c | 94 +++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 80 insertions(+), 14 deletions(-)
diff --git a/libavcodec/dca_parser.c b/libavcodec/dca_parser.c
index bde7dfe..0b09ba5 100644
--- a/libavcodec/dca_parser.c
+++ b/libavcodec/dca_parser.c
@@ -47,6 +47,14 @@ typedef struct DCAParseContext {
#define CORE_MARKER(state) ((state >> 16) & 0xFFFFFFFF)
#define EXSS_MARKER(state) (state & 0xFFFFFFFF)
+#define STATE_LE(state) (((state & 0xFF00FF00) >> 8) | ((state &
0x00FF00FF) << 8))
+#define STATE_14(state) (((state & 0x3FFF0000) >> 8) | ((state &
0x00003FFF) >> 6))
+
+#define CORE_FRAMESIZE(state) (((state >> 4) & 0x3FFF) + 1)
+#define EXSS_FRAMESIZE(state) ((state & 0x2000000000) ? \
+ ((state >> 5) & 0xFFFFF) + 1 : \
+ ((state >> 13) & 0x0FFFF) + 1)
+
/**
* Find the end of the current frame in the bitstream.
* @return the position of the first byte of the next frame, or -1
@@ -54,12 +62,13 @@ typedef struct DCAParseContext {
static int dca_find_frame_end(DCAParseContext *pc1, const uint8_t *buf,
int buf_size)
{
- int start_found, i;
+ int start_found, size, i;
uint64_t state;
ParseContext *pc = &pc1->pc;
start_found = pc->frame_start_found;
state = pc->state64;
+ size = pc1->size;
i = 0;
if (!start_found) {
@@ -80,15 +89,75 @@ static int dca_find_frame_end(DCAParseContext *pc1, const
uint8_t *buf,
}
}
}
+
if (start_found) {
for (; i < buf_size; i++) {
- pc1->size++;
+ size++;
state = (state << 8) | buf[i];
+
+ if (start_found == 1) {
+ switch (pc1->lastmarker) {
+ case DCA_SYNCWORD_CORE_BE:
+ if (size == 2) {
+ pc1->framesize = CORE_FRAMESIZE(state);
+ start_found = 2;
+ }
+ break;
+ case DCA_SYNCWORD_CORE_LE:
+ if (size == 2) {
+ pc1->framesize = CORE_FRAMESIZE(STATE_LE(state));
+ start_found = 2;
+ }
+ break;
+ case DCA_SYNCWORD_CORE_14B_BE:
+ if (size == 4) {
+ pc1->framesize = CORE_FRAMESIZE(STATE_14(state)) * 8 /
14 * 2;
+ start_found = 2;
+ }
+ break;
+ case DCA_SYNCWORD_CORE_14B_LE:
+ if (size == 4) {
+ pc1->framesize =
CORE_FRAMESIZE(STATE_14(STATE_LE(state))) * 8 / 14 * 2;
+ start_found = 2;
+ }
+ break;
+ case DCA_SYNCWORD_SUBSTREAM:
+ if (size == 6) {
+ pc1->framesize = EXSS_FRAMESIZE(state);
+ start_found = 2;
+ }
+ break;
+ default:
+ av_assert0(0);
+ }
+ continue;
+ }
+
+ if (pc1->lastmarker == DCA_SYNCWORD_CORE_BE) {
+ if (pc1->framesize > size + 2)
+ continue;
+
+ if (start_found == 2 && IS_EXSS_MARKER(state)) {
+ pc1->framesize = size + 2;
+ start_found = 3;
+ continue;
+ }
+
+ if (start_found == 3) {
+ if (size == pc1->framesize + 4) {
+ pc1->framesize += EXSS_FRAMESIZE(state);
+ start_found = 4;
+ }
+ continue;
+ }
+ }
+
+ if (pc1->framesize > size)
+ continue;
+
if (IS_MARKER(state) &&
(pc1->lastmarker == CORE_MARKER(state) ||
pc1->lastmarker == DCA_SYNCWORD_SUBSTREAM)) {
- if (pc1->framesize > pc1->size)
- continue;
pc->frame_start_found = 0;
pc->state64 = -1;
pc1->size = 0;
@@ -96,8 +165,10 @@ static int dca_find_frame_end(DCAParseContext *pc1, const
uint8_t *buf,
}
}
}
+
pc->frame_start_found = start_found;
pc->state64 = state;
+ pc1->size = size;
return END_NOT_FOUND;
}
@@ -110,11 +181,11 @@ static av_cold int dca_parse_init(AVCodecParserContext *s)
}
static int dca_parse_params(const uint8_t *buf, int buf_size, int *duration,
- int *sample_rate, int *framesize)
+ int *sample_rate)
{
GetBitContext gb;
uint8_t hdr[12 + AV_INPUT_BUFFER_PADDING_SIZE] = { 0 };
- int ret, sample_blocks, sr_code;
+ int ret, sample_blocks;
if (buf_size < 12)
return AVERROR_INVALIDDATA;
@@ -130,13 +201,8 @@ static int dca_parse_params(const uint8_t *buf, int
buf_size, int *duration,
return AVERROR_INVALIDDATA;
*duration = 256 * (sample_blocks / 8);
- *framesize = get_bits(&gb, 14) + 1;
- if (*framesize < 95)
- return AVERROR_INVALIDDATA;
-
- skip_bits(&gb, 6);
- sr_code = get_bits(&gb, 4);
- *sample_rate = avpriv_dca_sample_rates[sr_code];
+ skip_bits(&gb, 20);
+ *sample_rate = avpriv_dca_sample_rates[get_bits(&gb, 4)];
if (*sample_rate == 0)
return AVERROR_INVALIDDATA;
@@ -164,7 +230,7 @@ static int dca_parse(AVCodecParserContext *s,
AVCodecContext *avctx,
}
/* read the duration and sample rate from the frame header */
- if (!dca_parse_params(buf, buf_size, &duration, &sample_rate,
&pc1->framesize)) {
+ if (!dca_parse_params(buf, buf_size, &duration, &sample_rate)) {
if (!avctx->sample_rate)
avctx->sample_rate = sample_rate;
s->duration = av_rescale(duration, avctx->sample_rate, sample_rate);
--
2.8.1
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