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lavf: deobfuscate read_frame_internal().

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Split off packet parsing into a separate function. Parse full packets at
once and store them in a queue, eliminating the need for tracking
parsing state in AVStream.

The horrible unreadable loop in read_frame_internal() now isn't weirdly
ordered and doesn't contain evil gotos, so it should be much easier to
understand.

compute_pkt_fields() now invents slightly different timestamps for two
raw vc1 tests, due to has_b_frames being set a bit later. They shouldn't
be more wrong (or right) than previous ones.
This commit is contained in:
Anton Khirnov
2012-03-04 15:49:26 +01:00
parent dcee811505
commit 27c7ca9c12
6 changed files with 180 additions and 172 deletions
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314
libavformat/utils.c
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@@ -1011,6 +1011,105 @@ static void free_packet_buffer(AVPacketList **pkt_buf, AVPacketList **pkt_buf_en
*pkt_buf_end = NULL;
}
/**
* Parse a packet, add all split parts to parse_queue
*
* @param pkt packet to parse, NULL when flushing the parser at end of stream
*/
static int parse_packet(AVFormatContext *s, AVPacket *pkt, int stream_index)
{
AVPacket out_pkt = { 0 }, flush_pkt = { 0 };
AVStream *st = s->streams[stream_index];
uint8_t *data = pkt ? pkt->data : NULL;
int size = pkt ? pkt->size : 0;
int ret = 0, got_output = 0;
if (!pkt) {
av_init_packet(&flush_pkt);
pkt = &flush_pkt;
got_output = 1;
}
while (size > 0 || (pkt == &flush_pkt && got_output)) {
int len;
av_init_packet(&out_pkt);
len = av_parser_parse2(st->parser, st->codec,
&out_pkt.data, &out_pkt.size, data, size,
pkt->pts, pkt->dts, pkt->pos);
pkt->pts = pkt->dts = AV_NOPTS_VALUE;
/* increment read pointer */
data += len;
size -= len;
got_output = !!out_pkt.size;
if (!out_pkt.size)
continue;
/* set the duration */
out_pkt.duration = 0;
if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
if (st->codec->sample_rate > 0) {
out_pkt.duration = av_rescale_q_rnd(st->parser->duration,
(AVRational){ 1, st->codec->sample_rate },
st->time_base,
AV_ROUND_DOWN);
}
} else if (st->codec->time_base.num != 0 &&
st->codec->time_base.den != 0) {
out_pkt.duration = av_rescale_q_rnd(st->parser->duration,
st->codec->time_base,
st->time_base,
AV_ROUND_DOWN);
}
out_pkt.stream_index = st->index;
out_pkt.pts = st->parser->pts;
out_pkt.dts = st->parser->dts;
out_pkt.pos = st->parser->pos;
if (st->parser->key_frame == 1 ||
(st->parser->key_frame == -1 &&
st->parser->pict_type == AV_PICTURE_TYPE_I))
out_pkt.flags |= AV_PKT_FLAG_KEY;
compute_pkt_fields(s, st, st->parser, &out_pkt);
if ((s->iformat->flags & AVFMT_GENERIC_INDEX) &&
out_pkt.flags & AV_PKT_FLAG_KEY) {
ff_reduce_index(s, st->index);
av_add_index_entry(st, st->parser->frame_offset, out_pkt.dts,
0, 0, AVINDEX_KEYFRAME);
}
if (out_pkt.data == pkt->data && out_pkt.size == pkt->size) {
out_pkt.destruct = pkt->destruct;
pkt->destruct = NULL;
}
if ((ret = av_dup_packet(&out_pkt)) < 0)
goto fail;
if (!add_to_pktbuf(&s->parse_queue, &out_pkt, &s->parse_queue_end)) {
av_free_packet(&out_pkt);
ret = AVERROR(ENOMEM);
goto fail;
}
}
/* end of the stream => close and free the parser */
if (pkt == &flush_pkt) {
av_parser_close(st->parser);
st->parser = NULL;
}
fail:
av_free_packet(pkt);
return ret;
}
static int read_from_packet_buffer(AVPacketList **pkt_buffer,
AVPacketList **pkt_buffer_end,
AVPacket *pkt)
@@ -1026,154 +1125,86 @@ static int read_from_packet_buffer(AVPacketList **pkt_buffer,
return 0;
}
static int read_frame_internal(AVFormatContext *s, AVPacket *pkt)
{
AVStream *st;
int len, ret, i;
int ret = 0, i, got_packet = 0;
av_init_packet(pkt);
for(;;) {
/* select current input stream component */
st = s->cur_st;
if (st) {
if (!st->need_parsing || !st->parser) {
/* no parsing needed: we just output the packet as is */
/* raw data support */
*pkt = st->cur_pkt; st->cur_pkt.data= NULL;
compute_pkt_fields(s, st, NULL, pkt);
s->cur_st = NULL;
if ((s->iformat->flags & AVFMT_GENERIC_INDEX) &&
(pkt->flags & AV_PKT_FLAG_KEY) && pkt->dts != AV_NOPTS_VALUE) {
ff_reduce_index(s, st->index);
av_add_index_entry(st, pkt->pos, pkt->dts, 0, 0, AVINDEX_KEYFRAME);
}
break;
} else if (st->cur_len > 0 && st->discard < AVDISCARD_ALL) {
len = av_parser_parse2(st->parser, st->codec, &pkt->data, &pkt->size,
st->cur_ptr, st->cur_len,
st->cur_pkt.pts, st->cur_pkt.dts,
st->cur_pkt.pos);
st->cur_pkt.pts = AV_NOPTS_VALUE;
st->cur_pkt.dts = AV_NOPTS_VALUE;
/* increment read pointer */
st->cur_ptr += len;
st->cur_len -= len;
while (!got_packet && !s->parse_queue) {
AVStream *st;
AVPacket cur_pkt;
/* return packet if any */
if (pkt->size) {
got_packet:
pkt->duration = 0;
if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
if (st->codec->sample_rate > 0) {
pkt->duration = av_rescale_q_rnd(st->parser->duration,
(AVRational){ 1, st->codec->sample_rate },
st->time_base,
AV_ROUND_DOWN);
}
} else if (st->codec->time_base.num != 0 &&
st->codec->time_base.den != 0) {
pkt->duration = av_rescale_q_rnd(st->parser->duration,
st->codec->time_base,
st->time_base,
AV_ROUND_DOWN);
}
pkt->stream_index = st->index;
pkt->pts = st->parser->pts;
pkt->dts = st->parser->dts;
pkt->pos = st->parser->pos;
if (st->parser->key_frame == 1 ||
(st->parser->key_frame == -1 &&
st->parser->pict_type == AV_PICTURE_TYPE_I))
pkt->flags |= AV_PKT_FLAG_KEY;
if(pkt->data == st->cur_pkt.data && pkt->size == st->cur_pkt.size){
s->cur_st = NULL;
pkt->destruct= st->cur_pkt.destruct;
st->cur_pkt.destruct= NULL;
st->cur_pkt.data = NULL;
assert(st->cur_len == 0);
}else{
pkt->destruct = NULL;
}
compute_pkt_fields(s, st, st->parser, pkt);
if((s->iformat->flags & AVFMT_GENERIC_INDEX) && pkt->flags & AV_PKT_FLAG_KEY){
ff_reduce_index(s, st->index);
av_add_index_entry(st, st->parser->frame_offset, pkt->dts,
0, 0, AVINDEX_KEYFRAME);
}
break;
}
} else {
/* free packet */
av_free_packet(&st->cur_pkt);
s->cur_st = NULL;
}
} else {
AVPacket cur_pkt;
/* read next packet */
ret = av_read_packet(s, &cur_pkt);
if (ret < 0) {
if (ret == AVERROR(EAGAIN))
return ret;
/* return the last frames, if any */
for(i = 0; i < s->nb_streams; i++) {
st = s->streams[i];
if (st->parser && st->need_parsing) {
av_parser_parse2(st->parser, st->codec,
&pkt->data, &pkt->size,
NULL, 0,
AV_NOPTS_VALUE, AV_NOPTS_VALUE,
AV_NOPTS_VALUE);
if (pkt->size)
goto got_packet;
}
}
/* no more packets: really terminate parsing */
/* read next packet */
ret = av_read_packet(s, &cur_pkt);
if (ret < 0) {
if (ret == AVERROR(EAGAIN))
return ret;
/* flush the parsers */
for(i = 0; i < s->nb_streams; i++) {
st = s->streams[i];
if (st->parser && st->need_parsing)
parse_packet(s, NULL, st->index);
}
st = s->streams[cur_pkt.stream_index];
st->cur_pkt= cur_pkt;
/* all remaining packets are now in parse_queue =>
* really terminate parsing */
break;
}
ret = 0;
st = s->streams[cur_pkt.stream_index];
if(st->cur_pkt.pts != AV_NOPTS_VALUE &&
st->cur_pkt.dts != AV_NOPTS_VALUE &&
st->cur_pkt.pts < st->cur_pkt.dts){
av_log(s, AV_LOG_WARNING, "Invalid timestamps stream=%d, pts=%"PRId64", dts=%"PRId64", size=%d\n",
st->cur_pkt.stream_index,
st->cur_pkt.pts,
st->cur_pkt.dts,
st->cur_pkt.size);
// av_free_packet(&st->cur_pkt);
// return -1;
}
if (cur_pkt.pts != AV_NOPTS_VALUE &&
cur_pkt.dts != AV_NOPTS_VALUE &&
cur_pkt.pts < cur_pkt.dts) {
av_log(s, AV_LOG_WARNING, "Invalid timestamps stream=%d, pts=%"PRId64", dts=%"PRId64", size=%d\n",
cur_pkt.stream_index,
cur_pkt.pts,
cur_pkt.dts,
cur_pkt.size);
}
if (s->debug & FF_FDEBUG_TS)
av_log(s, AV_LOG_DEBUG, "av_read_packet stream=%d, pts=%"PRId64", dts=%"PRId64", size=%d, duration=%d, flags=%d\n",
cur_pkt.stream_index,
cur_pkt.pts,
cur_pkt.dts,
cur_pkt.size,
cur_pkt.duration,
cur_pkt.flags);
if(s->debug & FF_FDEBUG_TS)
av_log(s, AV_LOG_DEBUG, "av_read_packet stream=%d, pts=%"PRId64", dts=%"PRId64", size=%d, duration=%d, flags=%d\n",
st->cur_pkt.stream_index,
st->cur_pkt.pts,
st->cur_pkt.dts,
st->cur_pkt.size,
st->cur_pkt.duration,
st->cur_pkt.flags);
s->cur_st = st;
st->cur_ptr = st->cur_pkt.data;
st->cur_len = st->cur_pkt.size;
if (st->need_parsing && !st->parser && !(s->flags & AVFMT_FLAG_NOPARSE)) {
st->parser = av_parser_init(st->codec->codec_id);
if (!st->parser) {
/* no parser available: just output the raw packets */
st->need_parsing = AVSTREAM_PARSE_NONE;
}else if(st->need_parsing == AVSTREAM_PARSE_HEADERS){
st->parser->flags |= PARSER_FLAG_COMPLETE_FRAMES;
}else if(st->need_parsing == AVSTREAM_PARSE_FULL_ONCE){
st->parser->flags |= PARSER_FLAG_ONCE;
}
if (st->need_parsing && !st->parser && !(s->flags & AVFMT_FLAG_NOPARSE)) {
st->parser = av_parser_init(st->codec->codec_id);
if (!st->parser) {
/* no parser available: just output the raw packets */
st->need_parsing = AVSTREAM_PARSE_NONE;
} else if(st->need_parsing == AVSTREAM_PARSE_HEADERS) {
st->parser->flags |= PARSER_FLAG_COMPLETE_FRAMES;
} else if(st->need_parsing == AVSTREAM_PARSE_FULL_ONCE) {
st->parser->flags |= PARSER_FLAG_ONCE;
}
}
if (!st->need_parsing || !st->parser) {
/* no parsing needed: we just output the packet as is */
*pkt = cur_pkt;
compute_pkt_fields(s, st, NULL, pkt);
if ((s->iformat->flags & AVFMT_GENERIC_INDEX) &&
(pkt->flags & AV_PKT_FLAG_KEY) && pkt->dts != AV_NOPTS_VALUE) {
ff_reduce_index(s, st->index);
av_add_index_entry(st, pkt->pos, pkt->dts, 0, 0, AVINDEX_KEYFRAME);
}
got_packet = 1;
} else if (st->discard < AVDISCARD_ALL) {
if ((ret = parse_packet(s, &cur_pkt, cur_pkt.stream_index)) < 0)
return ret;
} else {
/* free packet */
av_free_packet(&cur_pkt);
}
}
if (!got_packet && s->parse_queue)
ret = read_from_packet_buffer(&s->parse_queue, &s->parse_queue_end, pkt);
if(s->debug & FF_FDEBUG_TS)
av_log(s, AV_LOG_DEBUG, "read_frame_internal stream=%d, pts=%"PRId64", dts=%"PRId64", size=%d, duration=%d, flags=%d\n",
pkt->stream_index,
@@ -1183,7 +1214,7 @@ static int read_frame_internal(AVFormatContext *s, AVPacket *pkt)
pkt->duration,
pkt->flags);
return 0;
return ret;
}
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
@@ -1242,6 +1273,7 @@ int av_read_frame(AVFormatContext *s, AVPacket *pkt)
/* XXX: suppress the packet queue */
static void flush_packet_queue(AVFormatContext *s)
{
free_packet_buffer(&s->parse_queue, &s->parse_queue_end);
free_packet_buffer(&s->packet_buffer, &s->packet_buffer_end);
free_packet_buffer(&s->raw_packet_buffer, &s->raw_packet_buffer_end);
@@ -1280,8 +1312,6 @@ void ff_read_frame_flush(AVFormatContext *s)
flush_packet_queue(s);
s->cur_st = NULL;
/* for each stream, reset read state */
for(i = 0; i < s->nb_streams; i++) {
st = s->streams[i];
@@ -1289,14 +1319,10 @@ void ff_read_frame_flush(AVFormatContext *s)
if (st->parser) {
av_parser_close(st->parser);
st->parser = NULL;
av_free_packet(&st->cur_pkt);
}
st->last_IP_pts = AV_NOPTS_VALUE;
st->cur_dts = AV_NOPTS_VALUE; /* we set the current DTS to an unspecified origin */
st->reference_dts = AV_NOPTS_VALUE;
/* fail safe */
st->cur_ptr = NULL;
st->cur_len = 0;
st->probe_packets = MAX_PROBE_PACKETS;
@@ -1874,8 +1900,6 @@ static void estimate_timings_from_pts(AVFormatContext *ic, int64_t old_offset)
int64_t filesize, offset, duration;
int retry=0;
ic->cur_st = NULL;
/* flush packet queue */
flush_packet_queue(ic);
@@ -1887,7 +1911,6 @@ static void estimate_timings_from_pts(AVFormatContext *ic, int64_t old_offset)
if (st->parser) {
av_parser_close(st->parser);
st->parser= NULL;
av_free_packet(&st->cur_pkt);
}
}
@@ -2560,7 +2583,6 @@ void avformat_free_context(AVFormatContext *s)
st = s->streams[i];
if (st->parser) {
av_parser_close(st->parser);
av_free_packet(&st->cur_pkt);
}
if (st->attached_pic.data)
av_free_packet(&st->attached_pic);