FFmpeg4/libavformat/webm_chunk.c

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2023-07-02 12:20:28 +00:00
/*
* Copyright (c) 2015, Vignesh Venkatasubramanian
*
* 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
*/
/**
* @file WebM Chunk Muxer
* The chunk muxer enables writing WebM Live chunks where there is a header
* chunk, followed by data chunks where each Cluster is written out as a Chunk.
*/
#include "avformat.h"
#include "avio.h"
#include "avio_internal.h"
#include "internal.h"
#include "libavutil/log.h"
#include "libavutil/opt.h"
#include "libavutil/mathematics.h"
#define MAX_FILENAME_SIZE 1024
typedef struct WebMChunkContext {
const AVClass *class;
char *header_filename;
int chunk_duration;
int chunk_index;
char *http_method;
uint64_t duration_written;
int64_t prev_pts;
AVFormatContext *avf;
int header_written;
} WebMChunkContext;
static int webm_chunk_init(AVFormatContext *s)
{
WebMChunkContext *wc = s->priv_data;
ff_const59 AVOutputFormat *oformat;
AVFormatContext *oc;
AVStream *st, *ost = s->streams[0];
AVDictionary *dict = NULL;
int ret;
// DASH Streams can only have one track per file.
if (s->nb_streams != 1)
return AVERROR(EINVAL);
if (!wc->header_filename) {
av_log(s, AV_LOG_ERROR, "No header filename provided\n");
return AVERROR(EINVAL);
}
wc->prev_pts = AV_NOPTS_VALUE;
oformat = av_guess_format("webm", s->url, "video/webm");
if (!oformat)
return AVERROR_MUXER_NOT_FOUND;
ret = avformat_alloc_output_context2(&wc->avf, oformat, NULL, NULL);
if (ret < 0)
return ret;
oc = wc->avf;
ff_format_set_url(oc, wc->header_filename);
wc->header_filename = NULL;
oc->interrupt_callback = s->interrupt_callback;
oc->max_delay = s->max_delay;
oc->flags = s->flags & ~AVFMT_FLAG_FLUSH_PACKETS;
oc->strict_std_compliance = s->strict_std_compliance;
oc->avoid_negative_ts = s->avoid_negative_ts;
oc->flush_packets = 0;
if ((ret = av_dict_copy(&oc->metadata, s->metadata, 0)) < 0)
return ret;
if (!(st = avformat_new_stream(oc, NULL)))
return AVERROR(ENOMEM);
if ((ret = avcodec_parameters_copy(st->codecpar, ost->codecpar)) < 0 ||
(ret = av_dict_copy(&st->metadata, ost->metadata, 0)) < 0)
return ret;
st->sample_aspect_ratio = ost->sample_aspect_ratio;
st->disposition = ost->disposition;
avpriv_set_pts_info(st, ost->pts_wrap_bits, ost->time_base.num,
ost->time_base.den);
if (wc->http_method)
if ((ret = av_dict_set(&dict, "method", wc->http_method, 0)) < 0)
return ret;
ret = s->io_open(s, &oc->pb, oc->url, AVIO_FLAG_WRITE, &dict);
av_dict_free(&dict);
if (ret < 0)
return ret;
oc->pb->seekable = 0;
if ((ret = av_dict_set_int(&dict, "dash", 1, 0)) < 0 ||
(ret = av_dict_set_int(&dict, "cluster_time_limit",
wc->chunk_duration, 0)) < 0 ||
(ret = av_dict_set_int(&dict, "live", 1, 0)) < 0)
goto fail;
ret = avformat_init_output(oc, &dict);
fail:
av_dict_free(&dict);
if (ret < 0)
return ret;
// Copy the timing info back to the original stream
// so that the timestamps of the packets are directly usable
avpriv_set_pts_info(ost, st->pts_wrap_bits, st->time_base.num,
st->time_base.den);
// This ensures that the timestamps will already be properly shifted
// when the packets arrive here, so we don't need to shift again.
s->avoid_negative_ts = oc->avoid_negative_ts;
s->internal->avoid_negative_ts_use_pts =
oc->internal->avoid_negative_ts_use_pts;
oc->avoid_negative_ts = 0;
return 0;
}
static int get_chunk_filename(AVFormatContext *s, char filename[MAX_FILENAME_SIZE])
{
WebMChunkContext *wc = s->priv_data;
if (!filename) {
return AVERROR(EINVAL);
}
if (av_get_frame_filename(filename, MAX_FILENAME_SIZE,
s->url, wc->chunk_index - 1) < 0) {
av_log(s, AV_LOG_ERROR, "Invalid chunk filename template '%s'\n", s->url);
return AVERROR(EINVAL);
}
return 0;
}
static int webm_chunk_write_header(AVFormatContext *s)
{
WebMChunkContext *wc = s->priv_data;
AVFormatContext *oc = wc->avf;
int ret;
ret = avformat_write_header(oc, NULL);
ff_format_io_close(s, &oc->pb);
wc->header_written = 1;
if (ret < 0)
return ret;
return 0;
}
static int chunk_start(AVFormatContext *s)
{
WebMChunkContext *wc = s->priv_data;
AVFormatContext *oc = wc->avf;
int ret;
ret = avio_open_dyn_buf(&oc->pb);
if (ret < 0)
return ret;
wc->chunk_index++;
return 0;
}
static int chunk_end(AVFormatContext *s, int flush)
{
WebMChunkContext *wc = s->priv_data;
AVFormatContext *oc = wc->avf;
int ret;
int buffer_size;
uint8_t *buffer;
AVIOContext *pb;
char filename[MAX_FILENAME_SIZE];
AVDictionary *options = NULL;
if (!oc->pb)
return 0;
if (flush)
// Flush the cluster in WebM muxer.
av_write_frame(oc, NULL);
buffer_size = avio_close_dyn_buf(oc->pb, &buffer);
oc->pb = NULL;
ret = get_chunk_filename(s, filename);
if (ret < 0)
goto fail;
if (wc->http_method)
if ((ret = av_dict_set(&options, "method", wc->http_method, 0)) < 0)
goto fail;
ret = s->io_open(s, &pb, filename, AVIO_FLAG_WRITE, &options);
av_dict_free(&options);
if (ret < 0)
goto fail;
avio_write(pb, buffer, buffer_size);
ff_format_io_close(s, &pb);
fail:
av_free(buffer);
return (ret < 0) ? ret : 0;
}
static int webm_chunk_write_packet(AVFormatContext *s, AVPacket *pkt)
{
WebMChunkContext *wc = s->priv_data;
AVFormatContext *oc = wc->avf;
AVStream *st = s->streams[pkt->stream_index];
int ret;
if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
if (wc->prev_pts != AV_NOPTS_VALUE)
wc->duration_written += av_rescale_q(pkt->pts - wc->prev_pts,
st->time_base,
(AVRational) {1, 1000});
wc->prev_pts = pkt->pts;
}
// For video, a new chunk is started only on key frames. For audio, a new
// chunk is started based on chunk_duration. Also, a new chunk is started
// unconditionally if there is no currently open chunk.
if (!oc->pb || (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
(pkt->flags & AV_PKT_FLAG_KEY)) ||
(st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
wc->duration_written >= wc->chunk_duration)) {
wc->duration_written = 0;
if ((ret = chunk_end(s, 1)) < 0 || (ret = chunk_start(s)) < 0) {
return ret;
}
}
// We only have one stream, so use the non-interleaving av_write_frame.
return av_write_frame(oc, pkt);
}
static int webm_chunk_write_trailer(AVFormatContext *s)
{
WebMChunkContext *wc = s->priv_data;
AVFormatContext *oc = wc->avf;
int ret;
if (!oc->pb) {
ret = chunk_start(s);
if (ret < 0)
return ret;
}
ret = av_write_trailer(oc);
if (ret < 0)
return ret;
return chunk_end(s, 0);
}
static void webm_chunk_deinit(AVFormatContext *s)
{
WebMChunkContext *wc = s->priv_data;
if (!wc->avf)
return;
if (wc->header_written)
ffio_free_dyn_buf(&wc->avf->pb);
else
ff_format_io_close(s, &wc->avf->pb);
avformat_free_context(wc->avf);
wc->avf = NULL;
}
#define OFFSET(x) offsetof(WebMChunkContext, x)
static const AVOption options[] = {
{ "chunk_start_index", "start index of the chunk", OFFSET(chunk_index), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
{ "header", "filename of the header where the initialization data will be written", OFFSET(header_filename), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },
{ "audio_chunk_duration", "duration of each chunk in milliseconds", OFFSET(chunk_duration), AV_OPT_TYPE_INT, {.i64 = 5000}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
{ "method", "set the HTTP method", OFFSET(http_method), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },
{ NULL },
};
static const AVClass webm_chunk_class = {
.class_name = "WebM Chunk Muxer",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
AVOutputFormat ff_webm_chunk_muxer = {
.name = "webm_chunk",
.long_name = NULL_IF_CONFIG_SMALL("WebM Chunk Muxer"),
.mime_type = "video/webm",
.extensions = "chk",
.flags = AVFMT_NOFILE | AVFMT_GLOBALHEADER | AVFMT_NEEDNUMBER |
AVFMT_TS_NONSTRICT,
.priv_data_size = sizeof(WebMChunkContext),
.init = webm_chunk_init,
.write_header = webm_chunk_write_header,
.write_packet = webm_chunk_write_packet,
.write_trailer = webm_chunk_write_trailer,
.deinit = webm_chunk_deinit,
.priv_class = &webm_chunk_class,
};