virtualenv/FFmpeg
1
0
Fork 0
mirror of https://github.com/FFmpeg/FFmpeg.git synced 2024-11-26 19:01:44 +02:00
Code Issues Releases Activity

Use a heuristic for describing the RTP packets using sample data

Browse Source 
Originally committed as revision 23165 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Martin Storsjö 2010-05-18 19:48:25 +00:00
parent e977af6f2e
commit 44bf251a42
2 changed files with 230 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
libavformat/movenc.h
View File

@ -51,6 +51,20 @@ typedef struct MOVIentry {
uint32_t flags;
} MOVIentry;
typedef struct HintSample {
uint8_t *data;
int size;
int sample_number;
int offset;
int own_data;
} HintSample;
typedef struct {
int size;
int len;
HintSample *samples;
} HintSampleQueue;
typedef struct MOVIndex {
int mode;
int entry;
@ -82,6 +96,8 @@ typedef struct MOVIndex {
uint32_t prev_rtp_ts;
int64_t cur_rtp_ts_unwrapped;
uint32_t max_packet_size;
HintSampleQueue sample_queue;
} MOVTrack;
typedef struct MOVMuxContext {

216
libavformat/movenchint.c
View File

@ -98,6 +98,188 @@ fail:
return ret;
}
/**
* Remove the first sample from the sample queue.
*/
static void sample_queue_pop(HintSampleQueue *queue)
{
if (queue->len <= 0)
return;
if (queue->samples[0].own_data)
av_free(queue->samples[0].data);
queue->len--;
memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len);
}
/**
* Empty the sample queue, releasing all memory.
*/
static void sample_queue_free(HintSampleQueue *queue)
{
int i;
for (i = 0; i < queue->len; i++)
if (queue->samples[i].own_data)
av_free(queue->samples[i].data);
av_freep(&queue->samples);
queue->len = 0;
queue->size = 0;
}
/**
* Add a reference to the sample data to the sample queue. The data is
* not copied. sample_queue_retain should be called before pkt->data
* is reused/freed.
*/
static void sample_queue_push(HintSampleQueue *queue, AVPacket *pkt, int sample)
{
/* No need to keep track of smaller samples, since describing them
* with immediates is more efficient. */
if (pkt->size <= 14)
return;
if (!queue->samples || queue->len >= queue->size) {
HintSample* samples;
queue->size += 10;
samples = av_realloc(queue->samples, sizeof(HintSample)*queue->size);
if (!samples)
return;
queue->samples = samples;
}
queue->samples[queue->len].data = pkt->data;
queue->samples[queue->len].size = pkt->size;
queue->samples[queue->len].sample_number = sample;
queue->samples[queue->len].offset = 0;
queue->samples[queue->len].own_data = 0;
queue->len++;
}
/**
* Make local copies of all referenced sample data in the queue.
*/
static void sample_queue_retain(HintSampleQueue *queue)
{
int i;
for (i = 0; i < queue->len; ) {
HintSample *sample = &queue->samples[i];
if (!sample->own_data) {
uint8_t* ptr = av_malloc(sample->size);
if (!ptr) {
/* Unable to allocate memory for this one, remove it */
memmove(queue->samples + i, queue->samples + i + 1,
sizeof(HintSample)*(queue->len - i - 1));
queue->len--;
continue;
}
memcpy(ptr, sample->data, sample->size);
sample->data = ptr;
sample->own_data = 1;
}
i++;
}
}
/**
* Find matches of needle[n_pos ->] within haystack. If a sufficiently
* large match is found, matching bytes before n_pos are included
* in the match, too (within the limits of the arrays).
*
* @param haystack buffer that may contain parts of needle
* @param h_len length of the haystack buffer
* @param needle buffer containing source data that have been used to
* construct haystack
* @param n_pos start position in needle used for looking for matches
* @param n_len length of the needle buffer
* @param match_h_offset_ptr offset of the first matching byte within haystack
* @param match_n_offset_ptr offset of the first matching byte within needle
* @param match_len_ptr length of the matched segment
* @return 0 if a match was found, < 0 if no match was found
*/
static int match_segments(const uint8_t *haystack, int h_len,
const uint8_t *needle, int n_pos, int n_len,
int *match_h_offset_ptr, int *match_n_offset_ptr,
int *match_len_ptr)
{
int h_pos;
for (h_pos = 0; h_pos < h_len; h_pos++) {
int match_len = 0;
int match_h_pos, match_n_pos;
/* Check how many bytes match at needle[n_pos] and haystack[h_pos] */
while (h_pos + match_len < h_len && n_pos + match_len < n_len &&
needle[n_pos + match_len] == haystack[h_pos + match_len])
match_len++;
if (match_len <= 8)
continue;
/* If a sufficiently large match was found, try to expand
* the matched segment backwards. */
match_h_pos = h_pos;
match_n_pos = n_pos;
while (match_n_pos > 0 && match_h_pos > 0 &&
needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {
match_n_pos--;
match_h_pos--;
match_len++;
}
if (match_len <= 14)
continue;
*match_h_offset_ptr = match_h_pos;
*match_n_offset_ptr = match_n_pos;
*match_len_ptr = match_len;
return 0;
}
return -1;
}
/**
* Look for segments in samples in the sample queue matching the data
* in ptr. Samples not matching are removed from the queue. If a match
* is found, the next time it will look for matches starting from the
* end of the previous matched segment.
*
* @param data data to find matches for in the sample queue
* @param len length of the data buffer
* @param queue samples used for looking for matching segments
* @param pos the offset in data of the matched segment
* @param match_sample the number of the sample that contained the match
* @param match_offset the offset of the matched segment within the sample
* @param match_len the length of the matched segment
* @return 0 if a match was found, < 0 if no match was found
*/
static int find_sample_match(const uint8_t *data, int len,
HintSampleQueue *queue, int *pos,
int *match_sample, int *match_offset,
int *match_len)
{
while (queue->len > 0) {
HintSample *sample = &queue->samples[0];
/* If looking for matches in a new sample, skip the first 5 bytes,
* since they often may be modified/removed in the output packet. */
if (sample->offset == 0 && sample->size > 5)
sample->offset = 5;
if (match_segments(data, len, sample->data, sample->offset,
sample->size, pos, match_offset, match_len) == 0) {
*match_sample = sample->sample_number;
/* Next time, look for matches at this offset, with a little
* margin to this match. */
sample->offset = *match_offset + *match_len + 5;
if (sample->offset + 10 >= sample->size)
sample_queue_pop(queue); /* Not enough useful data left */
return 0;
}
if (sample->offset < 10 && sample->size > 20) {
/* No match found from the start of the sample,
* try from the middle of the sample instead. */
sample->offset = sample->size/2;
} else {
/* No match for this sample, remove it */
sample_queue_pop(queue);
}
}
return -1;
}
static void output_immediate(const uint8_t *data, int size,
ByteIOContext *out, int *entries)
{
@ -118,10 +300,36 @@ static void output_immediate(const uint8_t *data, int size,
}
}
static void output_match(ByteIOContext *out, int match_sample,
int match_offset, int match_len, int *entries)
{
put_byte(out, 2); /* sample constructor */
put_byte(out, 0); /* track reference */
put_be16(out, match_len);
put_be32(out, match_sample);
put_be32(out, match_offset);
put_be16(out, 1); /* bytes per block */
put_be16(out, 1); /* samples per block */
(*entries)++;
}
static void describe_payload(const uint8_t *data, int size,
ByteIOContext *out, int *entries)
ByteIOContext *out, int *entries,
HintSampleQueue *queue)
{
/* Describe the payload using different constructors */
while (size > 0) {
int match_sample, match_offset, match_len, pos;
if (find_sample_match(data, size, queue, &pos, &match_sample,
&match_offset, &match_len) < 0)
break;
output_immediate(data, pos, out, entries);
data += pos;
size -= pos;
output_match(out, match_sample, match_offset, match_len, entries);
data += match_len;
size -= match_len;
}
output_immediate(data, size, out, entries);
}
@ -195,7 +403,7 @@ static int write_hint_packets(ByteIOContext *out, const uint8_t *data,
entries = 0;
/* Write one or more constructors describing the payload data */
describe_payload(data, packet_len, out, &entries);
describe_payload(data, packet_len, out, &entries, &trk->sample_queue);
data += packet_len;
size -= packet_len;
@ -230,6 +438,8 @@ int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
if (!rtp_ctx->pb)
return AVERROR(ENOMEM);
sample_queue_push(&trk->sample_queue, pkt, sample);
/* Feed the packet to the RTP muxer */
local_pkt = *pkt;
local_pkt.stream_index = 0;
@ -269,6 +479,7 @@ int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
ff_mov_write_packet(s, &hint_pkt);
done:
av_free(buf);
sample_queue_retain(&trk->sample_queue);
return ret;
}
@ -277,6 +488,7 @@ void ff_mov_close_hinting(MOVTrack *track) {
uint8_t *ptr;
av_freep(&track->enc);
sample_queue_free(&track->sample_queue);
if (!rtp_ctx)
return;
if (rtp_ctx->pb) {