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FFmpeg/libavformat/ffmenc.c
Michael Niedermayer 9829ec1a9c ffm: redesign header format to make it extensible 
Currently FFM files generated with one versions of ffmpeg generally
cannot be read by another.
By spliting data into chunks, more fields can saftely be appended to
chunks as well as new chunks added.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
2012-11-05 16:36:44 +01:00

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/*
* FFM (ffserver live feed) muxer
* Copyright (c) 2001 Fabrice Bellard
*
* 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/intreadwrite.h"
#include "libavutil/intfloat.h"
#include "libavutil/avassert.h"
#include "libavutil/parseutils.h"
#include "avformat.h"
#include "internal.h"
#include "ffm.h"
static void flush_packet(AVFormatContext *s)
{
FFMContext *ffm = s->priv_data;
int fill_size, h;
AVIOContext *pb = s->pb;
fill_size = ffm->packet_end - ffm->packet_ptr;
memset(ffm->packet_ptr, 0, fill_size);
av_assert1(avio_tell(pb) % ffm->packet_size == 0);
/* put header */
avio_wb16(pb, PACKET_ID);
avio_wb16(pb, fill_size);
avio_wb64(pb, ffm->dts);
h = ffm->frame_offset;
if (ffm->first_packet)
h |= 0x8000;
avio_wb16(pb, h);
avio_write(pb, ffm->packet, ffm->packet_end - ffm->packet);
avio_flush(pb);
/* prepare next packet */
ffm->frame_offset = 0; /* no key frame */
ffm->packet_ptr = ffm->packet;
ffm->first_packet = 0;
}
/* 'first' is true if first data of a frame */
static void ffm_write_data(AVFormatContext *s,
const uint8_t *buf, int size,
int64_t dts, int header)
{
FFMContext *ffm = s->priv_data;
int len;
if (header && ffm->frame_offset == 0) {
ffm->frame_offset = ffm->packet_ptr - ffm->packet + FFM_HEADER_SIZE;
ffm->dts = dts;
}
/* write as many packets as needed */
while (size > 0) {
len = ffm->packet_end - ffm->packet_ptr;
if (len > size)
len = size;
memcpy(ffm->packet_ptr, buf, len);
ffm->packet_ptr += len;
buf += len;
size -= len;
if (ffm->packet_ptr >= ffm->packet_end)
flush_packet(s);
}
}
static void write_header_chunk(AVIOContext *pb, AVIOContext *dpb, unsigned id)
{
uint8_t *dyn_buf;
int dyn_size= avio_close_dyn_buf(dpb, &dyn_buf);
avio_wb32(pb, id);
avio_wb32(pb, dyn_size);
avio_write(pb, dyn_buf, dyn_size);
av_free(dyn_buf);
}
static int ffm_write_header(AVFormatContext *s)
{
FFMContext *ffm = s->priv_data;
AVDictionaryEntry *t;
AVStream *st;
AVIOContext *pb = s->pb;
AVCodecContext *codec;
int bit_rate, i;
if (t = av_dict_get(s->metadata, "creation_time", NULL, 0)) {
int ret = av_parse_time(&ffm->start_time, t->value, 0);
if (ret < 0)
return ret;
}
ffm->packet_size = FFM_PACKET_SIZE;
/* header */
avio_wl32(pb, MKTAG('F', 'F', 'M', '2'));
avio_wb32(pb, ffm->packet_size);
avio_wb64(pb, 0); /* current write position */
if(avio_open_dyn_buf(&pb) < 0)
return AVERROR(ENOMEM);
avio_wb32(pb, s->nb_streams);
bit_rate = 0;
for(i=0;i<s->nb_streams;i++) {
st = s->streams[i];
bit_rate += st->codec->bit_rate;
}
avio_wb32(pb, bit_rate);
write_header_chunk(s->pb, pb, MKBETAG('M', 'A', 'I', 'N'));
/* list of streams */
for(i=0;i<s->nb_streams;i++) {
st = s->streams[i];
avpriv_set_pts_info(st, 64, 1, 1000000);
if(avio_open_dyn_buf(&pb) < 0)
return AVERROR(ENOMEM);
codec = st->codec;
/* generic info */
avio_wb32(pb, codec->codec_id);
avio_w8(pb, codec->codec_type);
avio_wb32(pb, codec->bit_rate);
avio_wb32(pb, codec->flags);
avio_wb32(pb, codec->flags2);
avio_wb32(pb, codec->debug);
if (codec->flags & CODEC_FLAG_GLOBAL_HEADER) {
avio_wb32(pb, codec->extradata_size);
avio_write(pb, codec->extradata, codec->extradata_size);
}
write_header_chunk(s->pb, pb, MKBETAG('C', 'O', 'M', 'M'));
if(avio_open_dyn_buf(&pb) < 0)
return AVERROR(ENOMEM);
/* specific info */
switch(codec->codec_type) {
case AVMEDIA_TYPE_VIDEO:
avio_wb32(pb, codec->time_base.num);
avio_wb32(pb, codec->time_base.den);
avio_wb16(pb, codec->width);
avio_wb16(pb, codec->height);
avio_wb16(pb, codec->gop_size);
avio_wb32(pb, codec->pix_fmt);
avio_w8(pb, codec->qmin);
avio_w8(pb, codec->qmax);
avio_w8(pb, codec->max_qdiff);
avio_wb16(pb, (int) (codec->qcompress * 10000.0));
avio_wb16(pb, (int) (codec->qblur * 10000.0));
avio_wb32(pb, codec->bit_rate_tolerance);
avio_put_str(pb, codec->rc_eq ? codec->rc_eq : "tex^qComp");
avio_wb32(pb, codec->rc_max_rate);
avio_wb32(pb, codec->rc_min_rate);
avio_wb32(pb, codec->rc_buffer_size);
avio_wb64(pb, av_double2int(codec->i_quant_factor));
avio_wb64(pb, av_double2int(codec->b_quant_factor));
avio_wb64(pb, av_double2int(codec->i_quant_offset));
avio_wb64(pb, av_double2int(codec->b_quant_offset));
avio_wb32(pb, codec->dct_algo);
avio_wb32(pb, codec->strict_std_compliance);
avio_wb32(pb, codec->max_b_frames);
avio_wb32(pb, codec->mpeg_quant);
avio_wb32(pb, codec->intra_dc_precision);
avio_wb32(pb, codec->me_method);
avio_wb32(pb, codec->mb_decision);
avio_wb32(pb, codec->nsse_weight);
avio_wb32(pb, codec->frame_skip_cmp);
avio_wb64(pb, av_double2int(codec->rc_buffer_aggressivity));
avio_wb32(pb, codec->codec_tag);
avio_w8(pb, codec->thread_count);
avio_wb32(pb, codec->coder_type);
avio_wb32(pb, codec->me_cmp);
avio_wb32(pb, codec->me_subpel_quality);
avio_wb32(pb, codec->me_range);
avio_wb32(pb, codec->keyint_min);
avio_wb32(pb, codec->scenechange_threshold);
avio_wb32(pb, codec->b_frame_strategy);
avio_wb64(pb, av_double2int(codec->qcompress));
avio_wb64(pb, av_double2int(codec->qblur));
avio_wb32(pb, codec->max_qdiff);
avio_wb32(pb, codec->refs);
write_header_chunk(s->pb, pb, MKBETAG('S', 'T', 'V', 'I'));
break;
case AVMEDIA_TYPE_AUDIO:
avio_wb32(pb, codec->sample_rate);
avio_wl16(pb, codec->channels);
avio_wl16(pb, codec->frame_size);
write_header_chunk(s->pb, pb, MKBETAG('S', 'T', 'A', 'U'));
break;
default:
return -1;
}
}
pb = s->pb;
avio_wb64(pb, 0); // end of header
/* flush until end of block reached */
while ((avio_tell(pb) % ffm->packet_size) != 0)
avio_w8(pb, 0);
avio_flush(pb);
/* init packet mux */
ffm->packet_ptr = ffm->packet;
ffm->packet_end = ffm->packet + ffm->packet_size - FFM_HEADER_SIZE;
av_assert0(ffm->packet_end >= ffm->packet);
ffm->frame_offset = 0;
ffm->dts = 0;
ffm->first_packet = 1;
return 0;
}
static int ffm_write_packet(AVFormatContext *s, AVPacket *pkt)
{
FFMContext *ffm = s->priv_data;
int64_t dts;
uint8_t header[FRAME_HEADER_SIZE+4];
int header_size = FRAME_HEADER_SIZE;
dts = ffm->start_time + pkt->dts;
/* packet size & key_frame */
header[0] = pkt->stream_index;
header[1] = 0;
if (pkt->flags & AV_PKT_FLAG_KEY)
header[1] |= FLAG_KEY_FRAME;
AV_WB24(header+2, pkt->size);
AV_WB24(header+5, pkt->duration);
AV_WB64(header+8, ffm->start_time + pkt->pts);
if (pkt->pts != pkt->dts) {
header[1] |= FLAG_DTS;
AV_WB32(header+16, pkt->pts - pkt->dts);
header_size += 4;
}
ffm_write_data(s, header, header_size, dts, 1);
ffm_write_data(s, pkt->data, pkt->size, dts, 0);
return 0;
}
static int ffm_write_trailer(AVFormatContext *s)
{
FFMContext *ffm = s->priv_data;
/* flush packets */
if (ffm->packet_ptr > ffm->packet)
flush_packet(s);
return 0;
}
AVOutputFormat ff_ffm_muxer = {
.name = "ffm",
.long_name = NULL_IF_CONFIG_SMALL("FFM (FFserver live feed)"),
.extensions = "ffm",
.priv_data_size = sizeof(FFMContext),
.audio_codec = AV_CODEC_ID_MP2,
.video_codec = AV_CODEC_ID_MPEG1VIDEO,
.write_header = ffm_write_header,
.write_packet = ffm_write_packet,
.write_trailer = ffm_write_trailer,
};
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