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Header elision muxing support.

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This only removes 2 bytes from MP3 and MP2 currently.
Up to 4 could be removed from MP3/MP2 though this might need a 2pass muxer.
Primitive code to remove headers from MPEG-1/2/4 is there too but for the
single file I tried it on (the one in the regression tests), it was a loss
because all video frames were >4096 byte, so that it is disabled ATM.

Originally committed as revision 11936 to svn://svn.ffmpeg.org/ffmpeg/trunk
pull/126/head
Michael Niedermayer 17 years ago
parent 3b4f69ae8c
commit a712d725c0
3 changed files with 191 additions and 32 deletions
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  1. 165
      libavformat/nutenc.c
  2. 4
      tests/libav.regression.ref
  3. 54
      tests/seek.regression.ref

165
libavformat/nutenc.c
Unescape View File

@ -21,6 +21,108 @@
#include "nut.h"
#include "tree.h"
#include "mpegaudiodata.h"
static int find_expected_header(AVCodecContext *c, int size, int key_frame, uint8_t out[64]){
int sample_rate= c->sample_rate;
if(size>4096)
return 0;
AV_WB24(out, 1);
if(c->codec_id == CODEC_ID_MPEG4){
if(key_frame){
return 3;
}else{
out[3]= 0xB6;
return 4;
}
}else if(c->codec_id == CODEC_ID_MPEG1VIDEO || c->codec_id == CODEC_ID_MPEG2VIDEO){
return 3;
}else if(c->codec_id == CODEC_ID_H264){
return 3;
}else if(c->codec_id == CODEC_ID_MP3 || c->codec_id == CODEC_ID_MP2){
int lsf, mpeg25, sample_rate_index, bitrate_index, frame_size;
int layer= c->codec_id == CODEC_ID_MP3 ? 3 : 2;
unsigned int header= 0xFFF00000;
lsf = sample_rate < (24000+32000)/2;
mpeg25 = sample_rate < (12000+16000)/2;
sample_rate <<= lsf + mpeg25;
if (sample_rate < (32000 + 44100)/2) sample_rate_index=2;
else if(sample_rate < (44100 + 48000)/2) sample_rate_index=0;
else sample_rate_index=1;
sample_rate= ff_mpa_freq_tab[sample_rate_index] >> (lsf + mpeg25);
for(bitrate_index=2; bitrate_index<30; bitrate_index++){
frame_size = ff_mpa_bitrate_tab[lsf][layer-1][bitrate_index>>1];
frame_size = (frame_size * 144000) / (sample_rate << lsf) + (bitrate_index&1);
if(frame_size == size)
break;
}
header |= (!lsf)<<19;
header |= (4-layer)<<17;
header |= 1<<16; //no crc
AV_WB32(out, header);
if(size <= 0)
return 2; //we guess theres no crc, if there is one the user clearly doesnt care about overhead
if(bitrate_index == 30)
return -1; //something is wrong ...
header |= (bitrate_index>>1)<<12;
header |= sample_rate_index<<10;
header |= (bitrate_index&1)<<9;
return 2; //FIXME actually put the needed ones in build_elision_headers()
return 3; //we guess that the private bit isnt set
//FIXME the above asumtations should be checked, if these turn out false too often something should be done
}
return 0;
}
static int find_header_idx(AVFormatContext *s, AVCodecContext *c, int size, int frame_type){
NUTContext *nut = s->priv_data;
uint8_t out[64];
int i;
int len= find_expected_header(c, size, frame_type, out);
//av_log(NULL, AV_LOG_ERROR, "expected_h len=%d size=%d codec_id=%d\n", len, size, c->codec_id);
for(i=1; i<nut->header_count; i++){
if( len == nut->header_len[i]
&& !memcmp(out, nut->header[i], len)){
// av_log(NULL, AV_LOG_ERROR, "found %d\n", i);
return i;
}
}
// av_log(NULL, AV_LOG_ERROR, "nothing found\n");
return 0;
}
static void build_elision_headers(AVFormatContext *s){
NUTContext *nut = s->priv_data;
int i;
//FIXME this is lame
//FIXME write a 2pass mode to find the maximal headers
const static uint8_t headers[][5]={
{3, 0x00, 0x00, 0x01},
{4, 0x00, 0x00, 0x01, 0xB6},
{2, 0xFF, 0xFA}, //mp3+crc
{2, 0xFF, 0xFB}, //mp3
{2, 0xFF, 0xFC}, //mp2+crc
{2, 0xFF, 0xFD}, //mp2
};
nut->header_count= 7;
for(i=1; i<nut->header_count; i++){
nut->header_len[i]= headers[i-1][0];
nut->header [i]= &headers[i-1][1];
}
}
static void build_frame_code(AVFormatContext *s){
NUTContext *nut = s->priv_data;
@ -63,6 +165,8 @@ static void build_frame_code(AVFormatContext *s){
ft->flags|= FLAG_SIZE_MSB | FLAG_CODED_PTS;
ft->stream_id= stream_id;
ft->size_mul=1;
if(is_audio)
ft->header_idx= find_header_idx(s, codec, -1, key_frame);
start2++;
}
}
@ -80,6 +184,7 @@ static void build_frame_code(AVFormatContext *s){
ft->size_mul=frame_bytes + 2;
ft->size_lsb=frame_bytes + pred;
ft->pts_delta=pts;
ft->header_idx= find_header_idx(s, codec, frame_bytes + pred, key_frame);
start2++;
}
}
@ -123,6 +228,8 @@ static void build_frame_code(AVFormatContext *s){
ft->size_mul= end3-start3;
ft->size_lsb= index - start3;
ft->pts_delta= pred_table[pred];
if(is_audio)
ft->header_idx= find_header_idx(s, codec, -1, key_frame);
}
}
}
@ -212,7 +319,8 @@ static void put_packet(NUTContext *nut, ByteIOContext *bc, ByteIOContext *dyn_bc
}
static void write_mainheader(NUTContext *nut, ByteIOContext *bc){
int i, j, tmp_pts, tmp_flags, tmp_stream, tmp_mul, tmp_size, tmp_fields;
int i, j, tmp_pts, tmp_flags, tmp_stream, tmp_mul, tmp_size, tmp_fields, tmp_head_idx;
int64_t tmp_match;
put_v(bc, 3); /* version */
put_v(bc, nut->avf->nb_streams);
@ -227,6 +335,8 @@ static void write_mainheader(NUTContext *nut, ByteIOContext *bc){
tmp_pts=0;
tmp_mul=1;
tmp_stream=0;
tmp_match= 1-(1LL<<62);
tmp_head_idx= 0;
for(i=0; i<256;){
tmp_fields=0;
tmp_size=0;
@ -236,6 +346,7 @@ static void write_mainheader(NUTContext *nut, ByteIOContext *bc){
if(tmp_stream != nut->frame_code[i].stream_id) tmp_fields=3;
if(tmp_size != nut->frame_code[i].size_lsb ) tmp_fields=4;
// if(tmp_res != nut->frame_code[i].res ) tmp_fields=5;
if(tmp_head_idx!=nut->frame_code[i].header_idx)tmp_fields=8;
tmp_pts = nut->frame_code[i].pts_delta;
tmp_flags = nut->frame_code[i].flags;
@ -243,6 +354,7 @@ static void write_mainheader(NUTContext *nut, ByteIOContext *bc){
tmp_mul = nut->frame_code[i].size_mul;
tmp_size = nut->frame_code[i].size_lsb;
// tmp_res = nut->frame_code[i].res;
tmp_head_idx= nut->frame_code[i].header_idx;
for(j=0; i<256; j++,i++){
if(i == 'N'){
@ -255,6 +367,7 @@ static void write_mainheader(NUTContext *nut, ByteIOContext *bc){
if(nut->frame_code[i].size_mul != tmp_mul ) break;
if(nut->frame_code[i].size_lsb != tmp_size+j) break;
// if(nut->frame_code[i].res != tmp_res ) break;
if(nut->frame_code[i].header_idx!= tmp_head_idx) break;
}
if(j != tmp_mul - tmp_size) tmp_fields=6;
@ -266,6 +379,13 @@ static void write_mainheader(NUTContext *nut, ByteIOContext *bc){
if(tmp_fields>3) put_v(bc, tmp_size);
if(tmp_fields>4) put_v(bc, 0 /*tmp_res*/);
if(tmp_fields>5) put_v(bc, j);
if(tmp_fields>6) put_v(bc, tmp_match);
if(tmp_fields>7) put_v(bc, tmp_head_idx);
}
put_v(bc, nut->header_count-1);
for(i=1; i<nut->header_count; i++){
put_v(bc, nut->header_len[i]);
put_buffer(bc, nut->header[i], nut->header_len[i]);
}
}
@ -419,6 +539,7 @@ static int write_header(AVFormatContext *s){
}
nut->max_distance = MAX_DISTANCE;
build_elision_headers(s);
build_frame_code(s);
assert(nut->frame_code['N'].flags == FLAG_INVALID);
@ -444,17 +565,40 @@ static int get_needed_flags(NUTContext *nut, StreamContext *nus, FrameCode *fc,
if(pkt->size > 2*nut->max_distance ) flags |= FLAG_CHECKSUM;
if(FFABS(pkt->pts - nus->last_pts)
> nus->max_pts_distance) flags |= FLAG_CHECKSUM;
if( pkt->size < nut->header_len[fc->header_idx]
|| (pkt->size > 4096 && fc->header_idx)
|| memcmp(pkt->data, nut->header[fc->header_idx], nut->header_len[fc->header_idx]))
flags |= FLAG_HEADER_IDX;
return flags | (fc->flags & FLAG_CODED);
}
static int find_best_header_idx(NUTContext *nut, AVPacket *pkt){
int i;
int best_i = 0;
int best_len= 0;
if(pkt->size > 4096)
return 0;
for(i=1; i<nut->header_count; i++){
if( pkt->size >= nut->header_len[i]
&& nut->header_len[i] > best_len
&& !memcmp(pkt->data, nut->header[i], nut->header_len[i])){
best_i= i;
best_len= nut->header_len[i];
}
}
return best_i;
}
static int write_packet(AVFormatContext *s, AVPacket *pkt){
NUTContext *nut = s->priv_data;
StreamContext *nus= &nut->stream[pkt->stream_index];
ByteIOContext *bc = s->pb, *dyn_bc;
FrameCode *fc;
int64_t coded_pts;
int best_length, frame_code, flags, needed_flags, i;
int best_length, frame_code, flags, needed_flags, i, header_idx, best_header_idx;
int key_frame = !!(pkt->flags & PKT_FLAG_KEY);
int store_sp=0;
int ret;
@ -503,6 +647,8 @@ static int write_packet(AVFormatContext *s, AVPacket *pkt){
if(ff_lsb2full(nus, coded_pts) != pkt->pts)
coded_pts= pkt->pts + (1<<nus->msb_pts_shift);
best_header_idx= find_best_header_idx(nut, pkt);
best_length=INT_MAX;
frame_code= -1;
for(i=0; i<256; i++){
@ -539,6 +685,17 @@ static int write_packet(AVFormatContext *s, AVPacket *pkt){
if(flags & FLAG_CODED_PTS)
length += get_length(coded_pts);
if( (flags & FLAG_CODED)
&& nut->header_len[best_header_idx] > nut->header_len[fc->header_idx]+1){
flags |= FLAG_HEADER_IDX;
}
if(flags & FLAG_HEADER_IDX){
length += 1 - nut->header_len[best_header_idx];
}else{
length -= nut->header_len[fc->header_idx];
}
length*=4;
length+= !(flags & FLAG_CODED_PTS);
length+= !(flags & FLAG_CHECKSUM);
@ -552,6 +709,7 @@ static int write_packet(AVFormatContext *s, AVPacket *pkt){
fc= &nut->frame_code[frame_code];
flags= fc->flags;
needed_flags= get_needed_flags(nut, nus, fc, pkt);
header_idx= fc->header_idx;
init_checksum(bc, ff_crc04C11DB7_update, 0);
put_byte(bc, frame_code);
@ -562,11 +720,12 @@ static int write_packet(AVFormatContext *s, AVPacket *pkt){
if(flags & FLAG_STREAM_ID) put_v(bc, pkt->stream_index);
if(flags & FLAG_CODED_PTS) put_v(bc, coded_pts);
if(flags & FLAG_SIZE_MSB) put_v(bc, pkt->size / fc->size_mul);
if(flags & FLAG_HEADER_IDX) put_v(bc, header_idx= best_header_idx);
if(flags & FLAG_CHECKSUM) put_le32(bc, get_checksum(bc));
else get_checksum(bc);
put_buffer(bc, pkt->data, pkt->size);
put_buffer(bc, pkt->data + nut->header_len[header_idx], pkt->size - nut->header_len[header_idx]);
nus->last_flags= flags;
//FIXME just store one per syncpoint

4
tests/libav.regression.ref
Unescape View File

@ -30,8 +30,8 @@ f8ad5bd78f4d012a8ce9570aa395ac54 *./tests/data/b-libav.flv
2ba41cf880aa5cb87e8a08fdb735398d *./tests/data/b-libav.gxf
814640 ./tests/data/b-libav.gxf
./tests/data/b-libav.gxf CRC=0xa376c09e
868101eb2d9f8fe128f84399d450633e *./tests/data/b-libav.nut
329785 ./tests/data/b-libav.nut
7e8f5cfb9c1c0ac60260a10e2f72f3ea *./tests/data/b-libav.nut
329347 ./tests/data/b-libav.nut
./tests/data/b-libav.nut CRC=0x400c29e9
43238b15f1012aa27536c2be20bb2383 *./tests/data/b-libav.mkv
329854 ./tests/data/b-libav.mkv

54
tests/seek.regression.ref
Unescape View File

@ -3193,59 +3193,59 @@ ret: 0 st:-1 ts:-0.645825 flags:1
ret: 0 st: 1 dts:0.500000 pts:0.500000 pos:-1 size:208 flags:1
----------------
tests/data/b-libav.nut
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:243 size:28088 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:279 size:28088 flags:1
ret: 0 st:-1 ts:-1.000000 flags:0
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:243 size:28088 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:279 size:28088 flags:1
ret: 0 st:-1 ts:1.894167 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st: 0 ts:0.800000 flags:0
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st: 0 ts:-0.320000 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:243 size:28088 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:279 size:28088 flags:1
ret: 0 st: 1 ts:2.586122 flags:0
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st: 1 ts:1.462857 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st:-1 ts:0.365002 flags:0
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:243 size:28088 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:279 size:28088 flags:1
ret: 0 st:-1 ts:-0.740831 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:243 size:28088 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:279 size:28088 flags:1
ret: 0 st: 0 ts:2.160000 flags:0
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st: 0 ts:1.040000 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st: 1 ts:-0.052245 flags:0
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:243 size:28088 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:279 size:28088 flags:1
ret: 0 st: 1 ts:2.847347 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st:-1 ts:1.730004 flags:0
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st:-1 ts:0.624171 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st: 0 ts:-0.480000 flags:0
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:243 size:28088 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:279 size:28088 flags:1
ret: 0 st: 0 ts:2.400000 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st: 1 ts:1.306122 flags:0
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st: 1 ts:0.208980 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:243 size:28088 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:279 size:28088 flags:1
ret: 0 st:-1 ts:-0.904994 flags:0
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:243 size:28088 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:279 size:28088 flags:1
ret: 0 st:-1 ts:1.989173 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st: 0 ts:0.880000 flags:0
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st: 0 ts:-0.240000 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:243 size:28088 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:279 size:28088 flags:1
ret: 0 st: 1 ts:2.664490 flags:0
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st: 1 ts:1.567347 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st:-1 ts:0.460008 flags:0
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149135 size:27412 flags:1
ret: 0 st: 0 dts:0.480000 pts:0.480000 pos:149133 size:27412 flags:1
ret: 0 st:-1 ts:-0.645825 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:243 size:28088 flags:1
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:279 size:28088 flags:1
----------------
tests/data/b-libav.ogg
ret: 0 st: 0 dts:0.000000 pts:0.000000 pos:-1 size:2352 flags:1

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