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h264: Refactor decode_nal_units

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pull/64/head
Luca Barbato 11 years ago committed by Janne Grunau
parent c389a80494
commit e10fd08aa7
1 changed files with 122 additions and 59 deletions
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  1. 181
      libavcodec/h264.c

181
libavcodec/h264.c
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@ -1281,6 +1281,116 @@ int ff_set_ref_count(H264Context *h)
return 0;
}
static int find_start_code(const uint8_t *buf, int buf_size,
int buf_index, int next_avc)
{
// start code prefix search
for (; buf_index + 3 < next_avc; buf_index++)
// This should always succeed in the first iteration.
if (buf[buf_index] == 0 &&
buf[buf_index + 1] == 0 &&
buf[buf_index + 2] == 1)
break;
if (buf_index + 3 >= buf_size)
return buf_size;
return buf_index + 3;
}
static int get_avc_nalsize(H264Context *h, const uint8_t *buf,
int buf_size, int *buf_index)
{
int i, nalsize = 0;
if (*buf_index >= buf_size - h->nal_length_size)
return -1;
for (i = 0; i < h->nal_length_size; i++)
nalsize = (nalsize << 8) | buf[(*buf_index)++];
if (nalsize <= 0 || nalsize > buf_size - *buf_index) {
av_log(h->avctx, AV_LOG_ERROR,
"AVC: nal size %d\n", nalsize);
return -1;
}
return nalsize;
}
static int get_bit_length(H264Context *h, const uint8_t *buf,
const uint8_t *ptr, int dst_length,
int i, int next_avc)
{
if ((h->workaround_bugs & FF_BUG_AUTODETECT) && i + 3 < next_avc &&
buf[i] == 0x00 && buf[i + 1] == 0x00 &&
buf[i + 2] == 0x01 && buf[i + 3] == 0xE0)
h->workaround_bugs |= FF_BUG_TRUNCATED;
if (!(h->workaround_bugs & FF_BUG_TRUNCATED))
while (dst_length > 0 && ptr[dst_length - 1] == 0)
dst_length--;
if (!dst_length)
return 0;
return 8 * dst_length - decode_rbsp_trailing(h, ptr + dst_length - 1);
}
static int get_last_needed_nal(H264Context *h, const uint8_t *buf, int buf_size)
{
int next_avc = h->is_avc ? 0 : buf_size;
int nal_index = 0;
int buf_index = 0;
int nals_needed = 0;
while(1) {
int nalsize = 0;
int dst_length, bit_length, consumed;
const uint8_t *ptr;
if (buf_index >= next_avc) {
nalsize = get_avc_nalsize(h, buf, buf_size, &buf_index);
if (nalsize < 0)
break;
next_avc = buf_index + nalsize;
} else {
buf_index = find_start_code(buf, buf_size, buf_index, next_avc);
if (buf_index >= buf_size)
break;
}
ptr = ff_h264_decode_nal(h, buf + buf_index, &dst_length, &consumed,
next_avc - buf_index);
if (ptr == NULL || dst_length < 0)
return AVERROR_INVALIDDATA;
buf_index += consumed;
bit_length = get_bit_length(h, buf, ptr, dst_length,
buf_index, next_avc);
nal_index++;
/* packets can sometimes contain multiple PPS/SPS,
* e.g. two PAFF field pictures in one packet, or a demuxer
* which splits NALs strangely if so, when frame threading we
* can't start the next thread until we've read all of them */
switch (h->nal_unit_type) {
case NAL_SPS:
case NAL_PPS:
nals_needed = nal_index;
break;
case NAL_DPA:
case NAL_IDR_SLICE:
case NAL_SLICE:
init_get_bits(&h->gb, ptr, bit_length);
if (!get_ue_golomb(&h->gb))
nals_needed = nal_index;
}
}
return nals_needed;
}
static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
int parse_extradata)
{
@ -1289,7 +1399,6 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
int buf_index;
unsigned context_count;
int next_avc;
int pass = !(avctx->active_thread_type & FF_THREAD_FRAME);
int nals_needed = 0; ///< number of NALs that need decoding before the next frame thread starts
int nal_index;
int ret = 0;
@ -1302,7 +1411,10 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
ff_h264_reset_sei(h);
}
for (; pass <= 1; pass++) {
if (avctx->active_thread_type & FF_THREAD_FRAME)
nals_needed = get_last_needed_nal(h, buf, buf_size);
{
buf_index = 0;
context_count = 0;
next_avc = h->is_avc ? 0 : buf_size;
@ -1312,38 +1424,18 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
int dst_length;
int bit_length;
const uint8_t *ptr;
int i, nalsize = 0;
int nalsize = 0;
int err;
if (buf_index >= next_avc) {
if (buf_index >= buf_size - h->nal_length_size)
break;
nalsize = 0;
for (i = 0; i < h->nal_length_size; i++)
nalsize = (nalsize << 8) | buf[buf_index++];
if (nalsize <= 0 || nalsize > buf_size - buf_index) {
av_log(h->avctx, AV_LOG_ERROR,
"AVC: nal size %d\n", nalsize);
nalsize = get_avc_nalsize(h, buf, buf_size, &buf_index);
if (nalsize < 0)
break;
}
next_avc = buf_index + nalsize;
} else {
// start code prefix search
for (; buf_index + 3 < next_avc; buf_index++)
// This should always succeed in the first iteration.
if (buf[buf_index] == 0 &&
buf[buf_index + 1] == 0 &&
buf[buf_index + 2] == 1)
break;
if (buf_index + 3 >= buf_size) {
buf_index = buf_size;
buf_index = find_start_code(buf, buf_size, buf_index, next_avc);
if (buf_index >= buf_size)
break;
}
buf_index += 3;
if (buf_index >= next_avc)
continue;
}
hx = h->thread_context[context_count];
@ -1354,18 +1446,9 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
ret = -1;
goto end;
}
i = buf_index + consumed;
if ((h->workaround_bugs & FF_BUG_AUTODETECT) && i + 3 < next_avc &&
buf[i] == 0x00 && buf[i + 1] == 0x00 &&
buf[i + 2] == 0x01 && buf[i + 3] == 0xE0)
h->workaround_bugs |= FF_BUG_TRUNCATED;
if (!(h->workaround_bugs & FF_BUG_TRUNCATED))
while (dst_length > 0 && ptr[dst_length - 1] == 0)
dst_length--;
bit_length = !dst_length ? 0
: (8 * dst_length -
decode_rbsp_trailing(h, ptr + dst_length - 1));
bit_length = get_bit_length(h, buf, ptr, dst_length,
buf_index + consumed, next_avc);
if (h->avctx->debug & FF_DEBUG_STARTCODE)
av_log(h->avctx, AV_LOG_DEBUG,
@ -1380,26 +1463,6 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
buf_index += consumed;
nal_index++;
if (pass == 0) {
/* packets can sometimes contain multiple PPS/SPS,
* e.g. two PAFF field pictures in one packet, or a demuxer
* which splits NALs strangely if so, when frame threading we
* can't start the next thread until we've read all of them */
switch (hx->nal_unit_type) {
case NAL_SPS:
case NAL_PPS:
nals_needed = nal_index;
break;
case NAL_DPA:
case NAL_IDR_SLICE:
case NAL_SLICE:
init_get_bits(&hx->gb, ptr, bit_length);
if (!get_ue_golomb(&hx->gb))
nals_needed = nal_index;
}
continue;
}
if (avctx->skip_frame >= AVDISCARD_NONREF &&
h->nal_ref_idc == 0 &&
h->nal_unit_type != NAL_SEI)

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