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add FLV decoder metadata parsing 

patch by Allan Hsu % allan A counterpop P net %
date: Dec 12, 2006 12:19 PM
subject: Re: [Ffmpeg-devel] [PATCH] FLV decoder metadata reading

Originally committed as revision 7286 to svn://svn.ffmpeg.org/ffmpeg/trunk
tags/v0.5
Allan Hsu Guillaume Poirier 19 years ago
parent
06d1e5c2b6
commit
428cc588f2
1 changed files with 175 additions and 66 deletions
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  1. +175
    -66
      libavformat/flvdec.c

+ 175
- 66
libavformat/flvdec.c View File

@@ -40,6 +40,45 @@ static int flv_probe(AVProbeData *p)
return 0;
}

static void flv_set_audio_codec(AVFormatContext *s, AVStream *astream, int flv_codecid) {
AVCodecContext *acodec = astream->codec;
switch(flv_codecid) {
//no distinction between S16 and S8 PCM codec flags
case FLV_CODECID_PCM_BE:
acodec->codec_id = acodec->bits_per_sample == 8 ? CODEC_ID_PCM_S8 : CODEC_ID_PCM_S16BE; break;
case FLV_CODECID_PCM_LE:
acodec->codec_id = acodec->bits_per_sample == 8 ? CODEC_ID_PCM_S8 : CODEC_ID_PCM_S16LE; break;
case FLV_CODECID_ADPCM: acodec->codec_id = CODEC_ID_ADPCM_SWF; break;
case FLV_CODECID_MP3 : acodec->codec_id = CODEC_ID_MP3 ; astream->need_parsing = 1 ; break;
case FLV_CODECID_NELLYMOSER_8HZ_MONO:
acodec->sample_rate = 8000; //in case metadata does not otherwise declare samplerate
case FLV_CODECID_NELLYMOSER:
default:
av_log(s, AV_LOG_INFO, "Unsupported audio codec (%x)\n", flv_codecid >> FLV_AUDIO_CODECID_OFFSET);
acodec->codec_tag = flv_codecid >> FLV_AUDIO_CODECID_OFFSET;
}
}

static int flv_set_video_codec(AVFormatContext *s, AVStream *vstream, int flv_codecid) {
AVCodecContext *vcodec = vstream->codec;
switch(flv_codecid) {
case FLV_CODECID_H263 : vcodec->codec_id = CODEC_ID_FLV1 ; break;
case FLV_CODECID_SCREEN: vcodec->codec_id = CODEC_ID_FLASHSV; break;
case FLV_CODECID_VP6 : vcodec->codec_id = CODEC_ID_VP6F ;
if(vcodec->extradata_size != 1) {
vcodec->extradata_size = 1;
vcodec->extradata = av_malloc(1);
}
vcodec->extradata[0] = get_byte(&s->pb);
return 1; // 1 byte body size adjustment for flv_read_packet()
default:
av_log(s, AV_LOG_INFO, "Unsupported video codec (%x)\n", flv_codecid);
vcodec->codec_tag = flv_codecid;
}

return 0;
}

static int amf_get_string(ByteIOContext *ioc, char *buffer, int buffsize) {
int length = get_be16(ioc);
if(length >= buffsize) {
@@ -54,6 +93,135 @@ static int amf_get_string(ByteIOContext *ioc, char *buffer, int buffsize) {
return length;
}

static int amf_parse_object(AVFormatContext *s, AVStream *astream, AVStream *vstream, const char *key, unsigned int max_pos, int depth) {
AVCodecContext *acodec, *vcodec;
ByteIOContext *ioc;
AMFDataType amf_type;
char str_val[256];
double num_val;

num_val = 0;
ioc = &s->pb;

amf_type = get_byte(ioc);

switch(amf_type) {
case AMF_DATA_TYPE_NUMBER:
num_val = av_int2dbl(get_be64(ioc)); break;
case AMF_DATA_TYPE_BOOL:
num_val = get_byte(ioc); break;
case AMF_DATA_TYPE_STRING:
if(amf_get_string(ioc, str_val, sizeof(str_val)) < 0)
return -1;
break;
case AMF_DATA_TYPE_OBJECT: {
unsigned int keylen;

while(url_ftell(ioc) < max_pos - 2 && (keylen = get_be16(ioc))) {
url_fskip(ioc, keylen); //skip key string
if(amf_parse_object(s, NULL, NULL, NULL, max_pos, depth + 1) < 0)
return -1; //if we couldn't skip, bomb out.
}
if(get_byte(ioc) != AMF_END_OF_OBJECT)
return -1;
}
break;
case AMF_DATA_TYPE_NULL:
case AMF_DATA_TYPE_UNDEFINED:
case AMF_DATA_TYPE_UNSUPPORTED:
break; //these take up no additional space
case AMF_DATA_TYPE_MIXEDARRAY:
url_fskip(ioc, 4); //skip 32-bit max array index
while(url_ftell(ioc) < max_pos - 2 && amf_get_string(ioc, str_val, sizeof(str_val)) > 0) {
//this is the only case in which we would want a nested parse to not skip over the object
if(amf_parse_object(s, astream, vstream, str_val, max_pos, depth + 1) < 0)
return -1;
}
if(get_byte(ioc) != AMF_END_OF_OBJECT)
return -1;
break;
case AMF_DATA_TYPE_ARRAY: {
unsigned int arraylen, i;

arraylen = get_be32(ioc);
for(i = 0; i < arraylen && url_ftell(ioc) < max_pos - 1; i++) {
if(amf_parse_object(s, NULL, NULL, NULL, max_pos, depth + 1) < 0)
return -1; //if we couldn't skip, bomb out.
}
}
break;
case AMF_DATA_TYPE_DATE:
url_fskip(ioc, 8 + 2); //timestamp (double) and UTC offset (int16)
break;
default: //unsupported type, we couldn't skip
return -1;
}

if(depth == 1 && key) { //only look for metadata values when we are not nested and key != NULL
acodec = astream ? astream->codec : NULL;
vcodec = vstream ? vstream->codec : NULL;

if(amf_type == AMF_DATA_TYPE_BOOL) {
if(!strcmp(key, "stereo") && acodec) acodec->channels = num_val > 0 ? 2 : 1;
} else if(amf_type == AMF_DATA_TYPE_NUMBER) {
if(!strcmp(key, "duration")) s->duration = num_val * AV_TIME_BASE;
else if(!strcmp(key, "width") && vcodec && num_val > 0) vcodec->width = num_val;
else if(!strcmp(key, "height") && vcodec && num_val > 0) vcodec->height = num_val;
else if(!strcmp(key, "audiocodecid") && acodec) flv_set_audio_codec(s, astream, (int)num_val << FLV_AUDIO_CODECID_OFFSET);
else if(!strcmp(key, "videocodecid") && vcodec) flv_set_video_codec(s, vstream, (int)num_val);
else if(!strcmp(key, "audiosamplesize") && acodec && num_val >= 0) {
acodec->bits_per_sample = num_val;
//we may have to rewrite a previously read codecid because FLV only marks PCM endianness.
if(num_val == 8 && (acodec->codec_id == CODEC_ID_PCM_S16BE || acodec->codec_id == CODEC_ID_PCM_S16LE))
acodec->codec_id = CODEC_ID_PCM_S8;
}
else if(!strcmp(key, "audiosamplerate") && acodec && num_val >= 0) {
//some tools, like FLVTool2, write consistently approximate metadata sample rates
switch((int)num_val) {
case 44000: acodec->sample_rate = 44100 ; break;
case 22000: acodec->sample_rate = 22050 ; break;
case 11000: acodec->sample_rate = 11025 ; break;
case 5000 : acodec->sample_rate = 5512 ; break;
default : acodec->sample_rate = num_val;
}
}
}
}

return 0;
}

static int flv_read_metabody(AVFormatContext *s, unsigned int next_pos) {
AMFDataType type;
AVStream *stream, *astream, *vstream;
ByteIOContext *ioc;
int i, keylen;
char buffer[11]; //only needs to hold the string "onMetaData". Anything longer is something we don't want.

astream = NULL;
vstream = NULL;
keylen = 0;
ioc = &s->pb;

//first object needs to be "onMetaData" string
type = get_byte(ioc);
if(type != AMF_DATA_TYPE_STRING || amf_get_string(ioc, buffer, sizeof(buffer)) < 0 || strcmp(buffer, "onMetaData"))
return -1;

//find the streams now so that amf_parse_object doesn't need to do the lookup every time it is called.
for(i = 0; i < s->nb_streams; i++) {
stream = s->streams[i];
if (stream->codec->codec_type == CODEC_TYPE_AUDIO) astream = stream;
else if(stream->codec->codec_type == CODEC_TYPE_VIDEO) vstream = stream;
}

//parse the second object (we want a mixed array)
if(amf_parse_object(s, astream, vstream, buffer, next_pos, 0) < 0)
return -1;

return 0;
}

static int flv_read_header(AVFormatContext *s,
AVFormatParameters *ap)
{
@@ -114,43 +282,11 @@ static int flv_read_packet(AVFormatContext *s, AVPacket *pkt)
} else if (type == FLV_TAG_TYPE_VIDEO) {
is_audio=0;
flags = get_byte(&s->pb);
} else if (type == FLV_TAG_TYPE_META && size > 13+1+4) {
url_fskip(&s->pb, 13); //onMetaData blah
if(get_byte(&s->pb) == 8){
url_fskip(&s->pb, 4);
}
while(url_ftell(&s->pb) + 5 < next){
char tmp[128];
int type, len;
double d= 0;

if(amf_get_string(&s->pb, tmp, sizeof(tmp))<0)
break;

type= get_byte(&s->pb);
if(type == AMF_DATA_TYPE_NUMBER){
d= av_int2dbl(get_be64(&s->pb));
}else if(type == AMF_DATA_TYPE_STRING){
amf_get_string(&s->pb, NULL, 0);
}else if(type == AMF_DATA_TYPE_MIXEDARRAY){
//array
break;
}else if(type == AMF_DATA_TYPE_DATE){
d= av_int2dbl(get_be64(&s->pb));
get_be16(&s->pb);
}

if(!strcmp(tmp, "duration")){
s->duration = d*AV_TIME_BASE;
}else if(!strcmp(tmp, "videodatarate")){
}else if(!strcmp(tmp, "audiodatarate")){
}
}
url_fseek(&s->pb, next, SEEK_SET);
continue;
} else {
/* skip packet */
av_log(s, AV_LOG_ERROR, "skipping flv packet: type %d, size %d, flags %d\n", type, size, flags);
if (type == FLV_TAG_TYPE_META && size > 13+1+4)
flv_read_metabody(s, next);
else /* skip packet */
av_log(s, AV_LOG_ERROR, "skipping flv packet: type %d, size %d, flags %d\n", type, size, flags);
url_fseek(&s->pb, next, SEEK_SET);
continue;
}
@@ -194,44 +330,17 @@ static int flv_read_packet(AVFormatContext *s, AVPacket *pkt)
}

if(is_audio){
if(st->codec->sample_rate == 0){
if(!st->codec->sample_rate || !st->codec->bits_per_sample || (!st->codec->codec_id && !st->codec->codec_tag)) {
st->codec->channels = (flags & FLV_AUDIO_CHANNEL_MASK) == FLV_STEREO ? 2 : 1;
if((flags & FLV_AUDIO_CODECID_MASK) == FLV_CODECID_NELLYMOSER_8HZ_MONO)
st->codec->sample_rate= 8000;
else
st->codec->sample_rate = (44100 << ((flags & FLV_AUDIO_SAMPLERATE_MASK) >> FLV_AUDIO_SAMPLERATE_OFFSET) >> 3);
switch(flags & FLV_AUDIO_CODECID_MASK) {
case FLV_CODECID_PCM_BE: if (flags & FLV_AUDIO_SAMPLESIZE_MASK) st->codec->codec_id = CODEC_ID_PCM_S16BE;
else st->codec->codec_id = CODEC_ID_PCM_S8; break;
case FLV_CODECID_ADPCM : st->codec->codec_id = CODEC_ID_ADPCM_SWF; break;
case FLV_CODECID_MP3 : st->codec->codec_id = CODEC_ID_MP3 ; st->need_parsing = 1; break;
// this is not listed at FLV but at SWF, strange...
case FLV_CODECID_PCM_LE: if (flags & FLV_AUDIO_SAMPLESIZE_MASK) st->codec->codec_id = CODEC_ID_PCM_S16LE;
else st->codec->codec_id = CODEC_ID_PCM_S8; break;
default:
av_log(s, AV_LOG_INFO, "Unsupported audio codec (%x)\n", flags >> 4);
st->codec->codec_tag= (flags >> 4);
}
st->codec->bits_per_sample = (flags & FLV_AUDIO_SAMPLESIZE_MASK) ? 16 : 8;
flv_set_audio_codec(s, st, flags & FLV_AUDIO_CODECID_MASK);
}
}else{
switch(flags & FLV_VIDEO_CODECID_MASK){
case FLV_CODECID_H263 : st->codec->codec_id = CODEC_ID_FLV1 ; break;
case FLV_CODECID_SCREEN: st->codec->codec_id = CODEC_ID_FLASHSV; break;
case FLV_CODECID_VP6 :
st->codec->codec_id = CODEC_ID_VP6F;
if (st->codec->extradata_size != 1) {
st->codec->extradata_size = 1;
st->codec->extradata = av_malloc(1);
}
/* width and height adjustment */
st->codec->extradata[0] = get_byte(&s->pb);
size--;
break;
default:
av_log(s, AV_LOG_INFO, "Unsupported video codec (%x)\n", flags & FLV_VIDEO_CODECID_MASK);
st->codec->codec_tag = flags & FLV_VIDEO_CODECID_MASK;
}
size -= flv_set_video_codec(s, st, flags & FLV_VIDEO_CODECID_MASK);
}

ret= av_get_packet(&s->pb, pkt, size - 1);


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