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h264: decouple extradata parsing from the decoder 

This will allow decoupling the parser from the decoder.
This commit is contained in:
Anton Khirnov 2016-03-29 04:09:14 +02:00
parent 728d90a0c1
commit 98c97994c5
5 changed files with 159 additions and 130 deletions
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133
libavcodec/h264.c
View File

@ -278,117 +278,6 @@ fail:
return AVERROR(ENOMEM); // ff_h264_free_tables will clean up for us
}
static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
int parse_extradata);
/* There are (invalid) samples in the wild with mp4-style extradata, where the
* parameter sets are stored unescaped (i.e. as RBSP).
* This function catches the parameter set decoding failure and tries again
* after escaping it */
static int decode_extradata_ps_mp4(H264Context *h, const uint8_t *buf, int buf_size)
{
int ret;
ret = decode_nal_units(h, buf, buf_size, 1);
if (ret < 0 && !(h->avctx->err_recognition & AV_EF_EXPLODE)) {
GetByteContext gbc;
PutByteContext pbc;
uint8_t *escaped_buf;
int escaped_buf_size;
av_log(h->avctx, AV_LOG_WARNING,
"SPS decoding failure, trying again after escaping the NAL\n");
if (buf_size / 2 >= (INT16_MAX - AV_INPUT_BUFFER_PADDING_SIZE) / 3)
return AVERROR(ERANGE);
escaped_buf_size = buf_size * 3 / 2 + AV_INPUT_BUFFER_PADDING_SIZE;
escaped_buf = av_mallocz(escaped_buf_size);
if (!escaped_buf)
return AVERROR(ENOMEM);
bytestream2_init(&gbc, buf, buf_size);
bytestream2_init_writer(&pbc, escaped_buf, escaped_buf_size);
while (bytestream2_get_bytes_left(&gbc)) {
if (bytestream2_get_bytes_left(&gbc) >= 3 &&
bytestream2_peek_be24(&gbc) <= 3) {
bytestream2_put_be24(&pbc, 3);
bytestream2_skip(&gbc, 2);
} else
bytestream2_put_byte(&pbc, bytestream2_get_byte(&gbc));
}
escaped_buf_size = bytestream2_tell_p(&pbc);
AV_WB16(escaped_buf, escaped_buf_size - 2);
ret = decode_nal_units(h, escaped_buf, escaped_buf_size, 1);
av_freep(&escaped_buf);
if (ret < 0)
return ret;
}
return 0;
}
int ff_h264_decode_extradata(H264Context *h)
{
AVCodecContext *avctx = h->avctx;
int ret;
if (avctx->extradata[0] == 1) {
int i, cnt, nalsize;
unsigned char *p = avctx->extradata;
h->is_avc = 1;
if (avctx->extradata_size < 7) {
av_log(avctx, AV_LOG_ERROR,
"avcC %d too short\n", avctx->extradata_size);
return AVERROR_INVALIDDATA;
}
/* sps and pps in the avcC always have length coded with 2 bytes,
* so put a fake nal_length_size = 2 while parsing them */
h->nal_length_size = 2;
// Decode sps from avcC
cnt = *(p + 5) & 0x1f; // Number of sps
p += 6;
for (i = 0; i < cnt; i++) {
nalsize = AV_RB16(p) + 2;
if (p - avctx->extradata + nalsize > avctx->extradata_size)
return AVERROR_INVALIDDATA;
ret = decode_extradata_ps_mp4(h, p, nalsize);
if (ret < 0) {
av_log(avctx, AV_LOG_ERROR,
"Decoding sps %d from avcC failed\n", i);
return ret;
}
p += nalsize;
}
// Decode pps from avcC
cnt = *(p++); // Number of pps
for (i = 0; i < cnt; i++) {
nalsize = AV_RB16(p) + 2;
if (p - avctx->extradata + nalsize > avctx->extradata_size)
return AVERROR_INVALIDDATA;
ret = decode_extradata_ps_mp4(h, p, nalsize);
if (ret < 0) {
av_log(avctx, AV_LOG_ERROR,
"Decoding pps %d from avcC failed\n", i);
return ret;
}
p += nalsize;
}
// Store right nal length size that will be used to parse all other nals
h->nal_length_size = (avctx->extradata[4] & 0x03) + 1;
} else {
h->is_avc = 0;
ret = decode_nal_units(h, avctx->extradata, avctx->extradata_size, 1);
if (ret < 0)
return ret;
}
return 0;
}
static int h264_init_context(AVCodecContext *avctx, H264Context *h)
{
int i;
@ -462,7 +351,9 @@ av_cold int ff_h264_decode_init(AVCodecContext *avctx)
}
if (avctx->extradata_size > 0 && avctx->extradata) {
ret = ff_h264_decode_extradata(h);
ret = ff_h264_decode_extradata(avctx->extradata, avctx->extradata_size,
&h->ps, &h->is_avc, &h->nal_length_size,
avctx->err_recognition, avctx);
if (ret < 0) {
ff_h264_free_context(h);
return ret;
@ -919,8 +810,7 @@ static int get_last_needed_nal(H264Context *h)
return nals_needed;
}
static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
int parse_extradata)
static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
{
AVCodecContext *const avctx = h->avctx;
unsigned context_count = 0;
@ -956,19 +846,6 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
continue;
again:
/* Ignore every NAL unit type except PPS and SPS during extradata
* parsing. Decoding slices is not possible in codec init
* with frame-mt */
if (parse_extradata && HAVE_THREADS &&
(h->avctx->active_thread_type & FF_THREAD_FRAME) &&
(nal->type != NAL_PPS && nal->type != NAL_SPS)) {
if (nal->type < NAL_AUD || nal->type > NAL_AUXILIARY_SLICE)
av_log(avctx, AV_LOG_INFO,
"Ignoring NAL unit %d during extradata parsing\n",
nal->type);
nal->type = NAL_FF_IGNORE;
}
// FIXME these should stop being context-global variables
h->nal_ref_idc = nal->ref_idc;
h->nal_unit_type = nal->type;
@ -1183,7 +1060,7 @@ out:
return buf_index;
}
buf_index = decode_nal_units(h, buf, buf_size, 0);
buf_index = decode_nal_units(h, buf, buf_size);
if (buf_index < 0)
return AVERROR_INVALIDDATA;

1
libavcodec/h264.h
View File

@ -706,7 +706,6 @@ int ff_h264_decode_ref_pic_marking(H264Context *h, GetBitContext *gb,
int ff_generate_sliding_window_mmcos(H264Context *h, int first_slice);
void ff_h264_hl_decode_mb(const H264Context *h, H264SliceContext *sl);
int ff_h264_decode_extradata(H264Context *h);
int ff_h264_decode_init(AVCodecContext *avctx);
void ff_h264_decode_init_vlc(void);

144
libavcodec/h264_parse.c
View File

@ -16,6 +16,7 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "bytestream.h"
#include "get_bits.h"
#include "golomb.h"
#include "h264.h"
@ -305,3 +306,146 @@ int ff_h264_init_poc(int pic_field_poc[2], int *pic_poc,
return 0;
}
static int decode_extradata_ps(const uint8_t *data, int size, H264ParamSets *ps,
int is_avc, void *logctx)
{
H2645Packet pkt = { 0 };
int i, ret = 0;
ret = ff_h2645_packet_split(&pkt, data, size, logctx, is_avc, 2, AV_CODEC_ID_H264);
if (ret < 0)
goto fail;
for (i = 0; i < pkt.nb_nals; i++) {
H2645NAL *nal = &pkt.nals[i];
switch (nal->type) {
case NAL_SPS:
ret = ff_h264_decode_seq_parameter_set(&nal->gb, logctx, ps);
if (ret < 0)
goto fail;
break;
case NAL_PPS:
ret = ff_h264_decode_picture_parameter_set(&nal->gb, logctx, ps,
nal->size_bits);
if (ret < 0)
goto fail;
break;
default:
av_log(logctx, AV_LOG_VERBOSE, "Ignoring NAL type %d in extradata\n",
nal->type);
break;
}
}
fail:
ff_h2645_packet_uninit(&pkt);
return ret;
}
/* There are (invalid) samples in the wild with mp4-style extradata, where the
* parameter sets are stored unescaped (i.e. as RBSP).
* This function catches the parameter set decoding failure and tries again
* after escaping it */
static int decode_extradata_ps_mp4(const uint8_t *buf, int buf_size, H264ParamSets *ps,
int err_recognition, void *logctx)
{
int ret;
ret = decode_extradata_ps(buf, buf_size, ps, 1, logctx);
if (ret < 0 && !(err_recognition & AV_EF_EXPLODE)) {
GetByteContext gbc;
PutByteContext pbc;
uint8_t *escaped_buf;
int escaped_buf_size;
av_log(logctx, AV_LOG_WARNING,
"SPS decoding failure, trying again after escaping the NAL\n");
if (buf_size / 2 >= (INT16_MAX - AV_INPUT_BUFFER_PADDING_SIZE) / 3)
return AVERROR(ERANGE);
escaped_buf_size = buf_size * 3 / 2 + AV_INPUT_BUFFER_PADDING_SIZE;
escaped_buf = av_mallocz(escaped_buf_size);
if (!escaped_buf)
return AVERROR(ENOMEM);
bytestream2_init(&gbc, buf, buf_size);
bytestream2_init_writer(&pbc, escaped_buf, escaped_buf_size);
while (bytestream2_get_bytes_left(&gbc)) {
if (bytestream2_get_bytes_left(&gbc) >= 3 &&
bytestream2_peek_be24(&gbc) <= 3) {
bytestream2_put_be24(&pbc, 3);
bytestream2_skip(&gbc, 2);
} else
bytestream2_put_byte(&pbc, bytestream2_get_byte(&gbc));
}
escaped_buf_size = bytestream2_tell_p(&pbc);
AV_WB16(escaped_buf, escaped_buf_size - 2);
ret = decode_extradata_ps(escaped_buf, escaped_buf_size, ps, 1, logctx);
av_freep(&escaped_buf);
if (ret < 0)
return ret;
}
return 0;
}
int ff_h264_decode_extradata(const uint8_t *data, int size, H264ParamSets *ps,
int *is_avc, int *nal_length_size,
int err_recognition, void *logctx)
{
int ret;
if (data[0] == 1) {
int i, cnt, nalsize;
const uint8_t *p = data;
*is_avc = 1;
if (size < 7) {
av_log(logctx, AV_LOG_ERROR, "avcC %d too short\n", size);
return AVERROR_INVALIDDATA;
}
// Decode sps from avcC
cnt = *(p + 5) & 0x1f; // Number of sps
p += 6;
for (i = 0; i < cnt; i++) {
nalsize = AV_RB16(p) + 2;
if (p - data + nalsize > size)
return AVERROR_INVALIDDATA;
ret = decode_extradata_ps_mp4(p, nalsize, ps, err_recognition, logctx);
if (ret < 0) {
av_log(logctx, AV_LOG_ERROR,
"Decoding sps %d from avcC failed\n", i);
return ret;
}
p += nalsize;
}
// Decode pps from avcC
cnt = *(p++); // Number of pps
for (i = 0; i < cnt; i++) {
nalsize = AV_RB16(p) + 2;
if (p - data + nalsize > size)
return AVERROR_INVALIDDATA;
ret = decode_extradata_ps_mp4(p, nalsize, ps, err_recognition, logctx);
if (ret < 0) {
av_log(logctx, AV_LOG_ERROR,
"Decoding pps %d from avcC failed\n", i);
return ret;
}
p += nalsize;
}
// Store right nal length size that will be used to parse all other nals
*nal_length_size = (data[4] & 0x03) + 1;
} else {
*is_avc = 0;
ret = decode_extradata_ps(data, size, ps, 0, logctx);
if (ret < 0)
return ret;
}
return 0;
}

5
libavcodec/h264_parse.h
View File

@ -54,6 +54,7 @@ typedef struct H264POCContext {
struct SPS;
struct PPS;
struct H264ParamSets;
int ff_h264_pred_weight_table(GetBitContext *gb, const struct SPS *sps,
const int *ref_count, int slice_type_nos,
@ -82,4 +83,8 @@ int ff_h264_init_poc(int pic_field_poc[2], int *pic_poc,
const struct SPS *sps, H264POCContext *poc,
int picture_structure, int nal_ref_idc);
int ff_h264_decode_extradata(const uint8_t *data, int size, struct H264ParamSets *ps,
int *is_avc, int *nal_length_size,
int err_recognition, void *logctx);
#endif /* AVCODEC_H264_PARSE_H */

6
libavcodec/h264_parser.c
View File

@ -50,6 +50,8 @@ typedef struct H264ParseContext {
H264DSPContext h264dsp;
H264POCContext poc;
H264SEIContext sei;
int is_avc;
int nal_length_size;
int got_first;
} H264ParseContext;
@ -500,7 +502,9 @@ static int h264_parse(AVCodecParserContext *s,
// NB: estimate_timings_from_pts behaves exactly like this.
if (!avctx->has_b_frames)
h->low_delay = 1;
ff_h264_decode_extradata(h);
ff_h264_decode_extradata(avctx->extradata, avctx->extradata_size,
&p->ps, &p->is_avc, &p->nal_length_size,
avctx->err_recognition, avctx);
}
}