PeerStreamer

/*

 * FLV demuxer

 * Copyright (c) 2003 The FFmpeg Project

 *

 * This demuxer will generate a 1 byte extradata for VP6F content.

 * It is composed of:

 *  - upper 4bits: difference between encoded width and visible width

 *  - lower 4bits: difference between encoded height and visible height

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "libavutil/avstring.h"

#include "libavcodec/bytestream.h"

#include "libavcodec/mpeg4audio.h"

#include "avformat.h"

#include "flv.h"

typedef struct {

    int wrong_dts; ///< wrong dts due to negative cts

} FLVContext;

static int flv_probe(AVProbeData *p)

{

    const uint8_t *d;

    d = p->buf;

    if (d[0] == 'F' && d[1] == 'L' && d[2] == 'V' && d[3] < 5 && d[5]==0 && AV_RB32(d+5)>8) {

        return AVPROBE_SCORE_MAX;

    }

    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:

            acodec->codec_id = acodec->bits_per_coded_sample == 8 ? CODEC_ID_PCM_S8 :

#if HAVE_BIGENDIAN

                                CODEC_ID_PCM_S16BE;

#else

                                CODEC_ID_PCM_S16LE;

#endif

            break;

        case FLV_CODECID_PCM_LE:

            acodec->codec_id = acodec->bits_per_coded_sample == 8 ? CODEC_ID_PCM_S8 : CODEC_ID_PCM_S16LE; break;

        case FLV_CODECID_AAC  : acodec->codec_id = CODEC_ID_AAC;                                    break;

        case FLV_CODECID_ADPCM: acodec->codec_id = CODEC_ID_ADPCM_SWF;                              break;

        case FLV_CODECID_SPEEX:

            acodec->codec_id = CODEC_ID_SPEEX;

            acodec->sample_rate = 16000;

            break;

        case FLV_CODECID_MP3  : acodec->codec_id = CODEC_ID_MP3      ; astream->need_parsing = AVSTREAM_PARSE_FULL; break;

        case FLV_CODECID_NELLYMOSER_8KHZ_MONO:

            acodec->sample_rate = 8000; //in case metadata does not otherwise declare samplerate

        case FLV_CODECID_NELLYMOSER:

            acodec->codec_id = CODEC_ID_NELLYMOSER;

            break;

        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_SCREEN2: vcodec->codec_id = CODEC_ID_FLASHSV2; break;

        case FLV_CODECID_VP6   : vcodec->codec_id = CODEC_ID_VP6F   ;

        case FLV_CODECID_VP6A  :

            if(flv_codecid == FLV_CODECID_VP6A)

                vcodec->codec_id = CODEC_ID_VP6A;

            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()

        case FLV_CODECID_H264:

            vcodec->codec_id = CODEC_ID_H264;

            return 3; // not 4, reading packet type will consume one byte

        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 **buf)

{

    uint16_t len = get_be16(ioc);

    *buf = av_malloc(len+1);

    if (!*buf)

        return AVERROR_NOMEM;

    get_buffer(ioc, *buf, len);

    (*buf)[len] = '\0';

    return len;

}

static int amf_parse_object(AVFormatContext *s, AVStream *astream, AVStream *vstream, const char *key, int64_t max_pos, int depth) {

    AVCodecContext *acodec, *vcodec;

    ByteIOContext *ioc;

    AMFDataType amf_type;

    char *str = NULL;

    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) < 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) > 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, max_pos, depth + 1) < 0)

                    return -1;

                av_freep(&str);

            }

            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) {

            av_metadata_set2(&s->metadata, key, av_d2str(num_val), AV_METADATA_DONT_STRDUP_VAL);

        } else if(amf_type == AMF_DATA_TYPE_NUMBER) {

            av_metadata_set2(&s->metadata, key, av_d2str(num_val), AV_METADATA_DONT_STRDUP_VAL);

            if(!strcmp(key, "duration")) s->duration = num_val * AV_TIME_BASE;

            else if(!strcmp(key, "videodatarate") && vcodec && 0 <= (int)(num_val * 1024.0))

                vcodec->bit_rate = num_val * 1024.0;

        } else if (amf_type == AMF_DATA_TYPE_STRING)

            av_metadata_set2(&s->metadata, key, str,

                                   AV_METADATA_DONT_STRDUP_VAL);

    }

    return 0;

}

static int flv_read_metabody(AVFormatContext *s, int64_t next_pos) {

    AMFDataType type;

    AVStream *stream, *astream, *vstream;

    ByteIOContext *ioc;

    int i;

    char *buf = NULL; //only needs to hold the string "onMetaData". Anything longer is something we don't want.

    astream = NULL;

    vstream = NULL;

    ioc = s->pb;

    //first object needs to be "onMetaData" string

    type = get_byte(ioc);

    if (type != AMF_DATA_TYPE_STRING ||

        amf_get_string(ioc, &buf) < 0 || strcmp(buf, "onMetaData")) {

        av_freep(&buf);

        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, buf, next_pos, 0) < 0)

        return -1;

    av_freep(&buf);

    return 0;

}

static AVStream *create_stream(AVFormatContext *s, int is_audio){

    AVStream *st = av_new_stream(s, is_audio);

    if (!st)

        return NULL;

    st->codec->codec_type = is_audio ? CODEC_TYPE_AUDIO : CODEC_TYPE_VIDEO;

    av_set_pts_info(st, 32, 1, 1000); /* 32 bit pts in ms */

    return st;

}

static int flv_read_header(AVFormatContext *s,

                           AVFormatParameters *ap)

{

    int offset, flags;

    url_fskip(s->pb, 4);

    flags = get_byte(s->pb);

    /* old flvtool cleared this field */

    /* FIXME: better fix needed */

    if (!flags) {

        flags = FLV_HEADER_FLAG_HASVIDEO | FLV_HEADER_FLAG_HASAUDIO;

        av_log(s, AV_LOG_WARNING, "Broken FLV file, which says no streams present, this might fail\n");

    }

    if((flags & (FLV_HEADER_FLAG_HASVIDEO|FLV_HEADER_FLAG_HASAUDIO))

             != (FLV_HEADER_FLAG_HASVIDEO|FLV_HEADER_FLAG_HASAUDIO))

        s->ctx_flags |= AVFMTCTX_NOHEADER;

    if(flags & FLV_HEADER_FLAG_HASVIDEO){

        if(!create_stream(s, 0))

            return AVERROR(ENOMEM);

    }

    if(flags & FLV_HEADER_FLAG_HASAUDIO){

        if(!create_stream(s, 1))

            return AVERROR(ENOMEM);

    }

    offset = get_be32(s->pb);

    url_fseek(s->pb, offset, SEEK_SET);

    s->start_time = 0;

    return 0;

}

static int flv_get_extradata(AVFormatContext *s, AVStream *st, int size)

{

    av_free(st->codec->extradata);

    st->codec->extradata = av_mallocz(size + FF_INPUT_BUFFER_PADDING_SIZE);

    if (!st->codec->extradata)

        return AVERROR(ENOMEM);

    st->codec->extradata_size = size;

    get_buffer(s->pb, st->codec->extradata, st->codec->extradata_size);

    return 0;

}

static int flv_read_packet(AVFormatContext *s, AVPacket *pkt)

{

    FLVContext *flv = s->priv_data;

    int ret, i, type, size, flags, is_audio;

    int64_t next, pos;

    int64_t dts, pts = AV_NOPTS_VALUE;

    AVStream *st = NULL;

 for(;;){

    pos = url_ftell(s->pb);

    url_fskip(s->pb, 4); /* size of previous packet */

    type = get_byte(s->pb);

    size = get_be24(s->pb);

    dts = get_be24(s->pb);

    dts |= get_byte(s->pb) << 24;

//    av_log(s, AV_LOG_DEBUG, "type:%d, size:%d, dts:%d\n", type, size, dts);

    if (url_feof(s->pb))

        return AVERROR_EOF;

    url_fskip(s->pb, 3); /* stream id, always 0 */

    flags = 0;

    if(size == 0)

        continue;

    next= size + url_ftell(s->pb);

    if (type == FLV_TAG_TYPE_AUDIO) {

        is_audio=1;

        flags = get_byte(s->pb);

        size--;

    } else if (type == FLV_TAG_TYPE_VIDEO) {

        is_audio=0;

        flags = get_byte(s->pb);

        size--;

        if ((flags & 0xf0) == 0x50) /* video info / command frame */

            goto skip;

    } else {

        if (type == FLV_TAG_TYPE_META && size > 13+1+4)

            flv_read_metabody(s, next);

        else /* skip packet */

            av_log(s, AV_LOG_DEBUG, "skipping flv packet: type %d, size %d, flags %d\n", type, size, flags);

    skip:

        url_fseek(s->pb, next, SEEK_SET);

        continue;

    }

    /* skip empty data packets */

    if (!size)

        continue;

    /* now find stream */

    for(i=0;i<s->nb_streams;i++) {

        st = s->streams[i];

        if (st->id == is_audio)

            break;

    }

    if(i == s->nb_streams){

        av_log(s, AV_LOG_ERROR, "invalid stream\n");

        st= create_stream(s, is_audio);

        s->ctx_flags &= ~AVFMTCTX_NOHEADER;

    }

//    av_log(s, AV_LOG_DEBUG, "%d %X %d \n", is_audio, flags, st->discard);

    if(  (st->discard >= AVDISCARD_NONKEY && !((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_KEY ||         is_audio))

       ||(st->discard >= AVDISCARD_BIDIR  &&  ((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_DISP_INTER && !is_audio))

       || st->discard >= AVDISCARD_ALL

       ){

        url_fseek(s->pb, next, SEEK_SET);

        continue;

    }

    if ((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_KEY)

        av_add_index_entry(st, pos, dts, size, 0, AVINDEX_KEYFRAME);

    break;

 }

    // if not streamed and no duration from metadata then seek to end to find the duration from the timestamps

    if(!url_is_streamed(s->pb) && s->duration==AV_NOPTS_VALUE){

        int size;

        const int64_t pos= url_ftell(s->pb);

        const int64_t fsize= url_fsize(s->pb);

        url_fseek(s->pb, fsize-4, SEEK_SET);

        size= get_be32(s->pb);

        url_fseek(s->pb, fsize-3-size, SEEK_SET);

        if(size == get_be24(s->pb) + 11){

            uint32_t ts = get_be24(s->pb);

            ts |= get_byte(s->pb) << 24;

            s->duration = ts * (int64_t)AV_TIME_BASE / 1000;

        }

        url_fseek(s->pb, pos, SEEK_SET);

    }

    if(is_audio){

        if(!st->codec->channels || !st->codec->sample_rate || !st->codec->bits_per_coded_sample) {

            st->codec->channels = (flags & FLV_AUDIO_CHANNEL_MASK) == FLV_STEREO ? 2 : 1;

            st->codec->sample_rate = (44100 << ((flags & FLV_AUDIO_SAMPLERATE_MASK) >> FLV_AUDIO_SAMPLERATE_OFFSET) >> 3);

            st->codec->bits_per_coded_sample = (flags & FLV_AUDIO_SAMPLESIZE_MASK) ? 16 : 8;

        }

        if(!st->codec->codec_id){

            flv_set_audio_codec(s, st, flags & FLV_AUDIO_CODECID_MASK);

        }

    }else{

        size -= flv_set_video_codec(s, st, flags & FLV_VIDEO_CODECID_MASK);

    }

    if (st->codec->codec_id == CODEC_ID_AAC ||

        st->codec->codec_id == CODEC_ID_H264) {

        int type = get_byte(s->pb);

        size--;

        if (st->codec->codec_id == CODEC_ID_H264) {

            int32_t cts = (get_be24(s->pb)+0xff800000)^0xff800000; // sign extension

            pts = dts + cts;

            if (cts < 0) { // dts are wrong

                flv->wrong_dts = 1;

                av_log(s, AV_LOG_WARNING, "negative cts, previous timestamps might be wrong\n");

            }

            if (flv->wrong_dts)

                dts = AV_NOPTS_VALUE;

        }

        if (type == 0) {

            if ((ret = flv_get_extradata(s, st, size)) < 0)

                return ret;

            if (st->codec->codec_id == CODEC_ID_AAC) {

                MPEG4AudioConfig cfg;

                ff_mpeg4audio_get_config(&cfg, st->codec->extradata,

                                         st->codec->extradata_size);

                st->codec->channels = cfg.channels;

                st->codec->sample_rate = cfg.sample_rate;

                dprintf(s, "mp4a config channels %d sample rate %d\n",

                        st->codec->channels, st->codec->sample_rate);

            }

            return AVERROR(EAGAIN);

        }

    }

    /* skip empty data packets */

    if (!size)

        return AVERROR(EAGAIN);

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

    if (ret < 0) {

        return AVERROR(EIO);

    }

    /* note: we need to modify the packet size here to handle the last

       packet */

    pkt->size = ret;

    pkt->dts = dts;

    pkt->pts = pts == AV_NOPTS_VALUE ? dts : pts;

    pkt->stream_index = st->index;

    if (is_audio || ((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_KEY))

        pkt->flags |= PKT_FLAG_KEY;

    return ret;

}

AVInputFormat flv_demuxer = {

    "flv",

    NULL_IF_CONFIG_SMALL("FLV format"),

    sizeof(FLVContext),

    flv_probe,

    flv_read_header,

    flv_read_packet,

    .extensions = "flv",

    .value = CODEC_ID_FLV1,

};