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FFmpeg/libavformat/dashenc.c
Martin Storsjö 456e93bfdd dashenc: Adjust the start time of a segment to the end of the previous segment 
This is the same adjustment that the mp4 muxer does to the start
timestamp of fragments, since the timestamp of a sample in an mp4
file is implicit from the sum of earlier sample durations.

This avoids gaps in the timeline (which can stop dash.js from
playing it back), and makes sure the timestamp on the segmenter
level matches what the mp4 muxer actually writes into the segments.

This is only an issue if the AVPacket duration of the last
packet of a segment doesn't point to the actual start timestamp
of the next packet (the first in the next segment).

Signed-off-by: Martin Storsjö <martin@martin.st>
2014-12-17 09:43:08 +02:00

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/*
* MPEG-DASH ISO BMFF segmenter
* Copyright (c) 2014 Martin Storsjo
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "config.h"
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "libavutil/avstring.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"
#include "libavutil/opt.h"
#include "libavutil/time_internal.h"
#include "avc.h"
#include "avformat.h"
#include "avio_internal.h"
#include "internal.h"
#include "isom.h"
#include "os_support.h"
#include "url.h"
// See ISO/IEC 23009-1:2014 5.3.9.4.4
typedef enum {
DASH_TMPL_ID_UNDEFINED = -1,
DASH_TMPL_ID_ESCAPE,
DASH_TMPL_ID_REP_ID,
DASH_TMPL_ID_NUMBER,
DASH_TMPL_ID_BANDWIDTH,
DASH_TMPL_ID_TIME,
} DASHTmplId;
typedef struct Segment {
char file[1024];
int64_t start_pos;
int range_length, index_length;
int64_t time;
int duration;
int n;
} Segment;
typedef struct OutputStream {
AVFormatContext *ctx;
int ctx_inited;
uint8_t iobuf[32768];
URLContext *out;
int packets_written;
char initfile[1024];
int64_t init_start_pos;
int init_range_length;
int nb_segments, segments_size, segment_index;
Segment **segments;
int64_t first_dts, start_dts, end_dts;
int bit_rate;
char bandwidth_str[64];
char codec_str[100];
} OutputStream;
typedef struct DASHContext {
const AVClass *class; /* Class for private options. */
int window_size;
int extra_window_size;
int min_seg_duration;
int remove_at_exit;
int use_template;
int use_timeline;
int single_file;
OutputStream *streams;
int has_video, has_audio;
int64_t last_duration;
int64_t total_duration;
char availability_start_time[100];
char dirname[1024];
const char *single_file_name;
const char *init_seg_name;
const char *media_seg_name;
} DASHContext;
static int dash_write(void *opaque, uint8_t *buf, int buf_size)
{
OutputStream *os = opaque;
if (os->out)
ffurl_write(os->out, buf, buf_size);
return buf_size;
}
// RFC 6381
static void set_codec_str(AVFormatContext *s, AVCodecContext *codec,
char *str, int size)
{
const AVCodecTag *tags[2] = { NULL, NULL };
uint32_t tag;
if (codec->codec_type == AVMEDIA_TYPE_VIDEO)
tags[0] = ff_codec_movvideo_tags;
else if (codec->codec_type == AVMEDIA_TYPE_AUDIO)
tags[0] = ff_codec_movaudio_tags;
else
return;
tag = av_codec_get_tag(tags, codec->codec_id);
if (!tag)
return;
if (size < 5)
return;
AV_WL32(str, tag);
str[4] = '\0';
if (!strcmp(str, "mp4a") || !strcmp(str, "mp4v")) {
uint32_t oti;
tags[0] = ff_mp4_obj_type;
oti = av_codec_get_tag(tags, codec->codec_id);
if (oti)
av_strlcatf(str, size, ".%02x", oti);
else
return;
if (tag == MKTAG('m', 'p', '4', 'a')) {
if (codec->extradata_size >= 2) {
int aot = codec->extradata[0] >> 3;
if (aot == 31)
aot = ((AV_RB16(codec->extradata) >> 5) & 0x3f) + 32;
av_strlcatf(str, size, ".%d", aot);
}
} else if (tag == MKTAG('m', 'p', '4', 'v')) {
// Unimplemented, should output ProfileLevelIndication as a decimal number
av_log(s, AV_LOG_WARNING, "Incomplete RFC 6381 codec string for mp4v\n");
}
} else if (!strcmp(str, "avc1")) {
uint8_t *tmpbuf = NULL;
uint8_t *extradata = codec->extradata;
int extradata_size = codec->extradata_size;
if (!extradata_size)
return;
if (extradata[0] != 1) {
AVIOContext *pb;
if (avio_open_dyn_buf(&pb) < 0)
return;
if (ff_isom_write_avcc(pb, extradata, extradata_size) < 0) {
avio_close_dyn_buf(pb, &tmpbuf);
av_free(tmpbuf);
return;
}
extradata_size = avio_close_dyn_buf(pb, &extradata);
tmpbuf = extradata;
}
if (extradata_size >= 4)
av_strlcatf(str, size, ".%02x%02x%02x",
extradata[1], extradata[2], extradata[3]);
av_free(tmpbuf);
}
}
static void dash_free(AVFormatContext *s)
{
DASHContext *c = s->priv_data;
int i, j;
if (!c->streams)
return;
for (i = 0; i < s->nb_streams; i++) {
OutputStream *os = &c->streams[i];
if (os->ctx && os->ctx_inited)
av_write_trailer(os->ctx);
if (os->ctx && os->ctx->pb)
av_free(os->ctx->pb);
ffurl_close(os->out);
os->out = NULL;
if (os->ctx)
avformat_free_context(os->ctx);
for (j = 0; j < os->nb_segments; j++)
av_free(os->segments[j]);
av_free(os->segments);
}
av_freep(&c->streams);
}
static void output_segment_list(OutputStream *os, AVIOContext *out, DASHContext *c)
{
int i, start_index = 0, start_number = 1;
if (c->window_size) {
start_index = FFMAX(os->nb_segments - c->window_size, 0);
start_number = FFMAX(os->segment_index - c->window_size, 1);
}
if (c->use_template) {
int timescale = c->use_timeline ? os->ctx->streams[0]->time_base.den : AV_TIME_BASE;
avio_printf(out, "\t\t\t\t<SegmentTemplate timescale=\"%d\" ", timescale);
if (!c->use_timeline)
avio_printf(out, "duration=\"%"PRId64"\" ", c->last_duration);
avio_printf(out, "initialization=\"%s\" media=\"%s\" startNumber=\"%d\">\n", c->init_seg_name, c->media_seg_name, c->use_timeline ? start_number : 1);
if (c->use_timeline) {
int64_t cur_time = 0;
avio_printf(out, "\t\t\t\t\t<SegmentTimeline>\n");
for (i = start_index; i < os->nb_segments; ) {
Segment *seg = os->segments[i];
int repeat = 0;
avio_printf(out, "\t\t\t\t\t\t<S ");
if (i == start_index || seg->time != cur_time)
avio_printf(out, "t=\"%"PRId64"\" ", seg->time);
avio_printf(out, "d=\"%d\" ", seg->duration);
while (i + repeat + 1 < os->nb_segments &&
os->segments[i + repeat + 1]->duration == seg->duration &&
os->segments[i + repeat + 1]->time == os->segments[i + repeat]->time + os->segments[i + repeat]->duration)
repeat++;
if (repeat > 0)
avio_printf(out, "r=\"%d\" ", repeat);
avio_printf(out, "/>\n");
i += 1 + repeat;
cur_time += (1 + repeat) * seg->duration;
}
avio_printf(out, "\t\t\t\t\t</SegmentTimeline>\n");
}
avio_printf(out, "\t\t\t\t</SegmentTemplate>\n");
} else if (c->single_file) {
avio_printf(out, "\t\t\t\t<BaseURL>%s</BaseURL>\n", os->initfile);
avio_printf(out, "\t\t\t\t<SegmentList timescale=\"%d\" duration=\"%"PRId64"\" startNumber=\"%d\">\n", AV_TIME_BASE, c->last_duration, start_number);
avio_printf(out, "\t\t\t\t\t<Initialization range=\"%"PRId64"-%"PRId64"\" />\n", os->init_start_pos, os->init_start_pos + os->init_range_length - 1);
for (i = start_index; i < os->nb_segments; i++) {
Segment *seg = os->segments[i];
avio_printf(out, "\t\t\t\t\t<SegmentURL mediaRange=\"%"PRId64"-%"PRId64"\" ", seg->start_pos, seg->start_pos + seg->range_length - 1);
if (seg->index_length)
avio_printf(out, "indexRange=\"%"PRId64"-%"PRId64"\" ", seg->start_pos, seg->start_pos + seg->index_length - 1);
avio_printf(out, "/>\n");
}
avio_printf(out, "\t\t\t\t</SegmentList>\n");
} else {
avio_printf(out, "\t\t\t\t<SegmentList timescale=\"%d\" duration=\"%"PRId64"\" startNumber=\"%d\">\n", AV_TIME_BASE, c->last_duration, start_number);
avio_printf(out, "\t\t\t\t\t<Initialization sourceURL=\"%s\" />\n", os->initfile);
for (i = start_index; i < os->nb_segments; i++) {
Segment *seg = os->segments[i];
avio_printf(out, "\t\t\t\t\t<SegmentURL media=\"%s\" />\n", seg->file);
}
avio_printf(out, "\t\t\t\t</SegmentList>\n");
}
}
static DASHTmplId dash_read_tmpl_id(const char *identifier, char *format_tag,
size_t format_tag_size, const char **ptr) {
const char *next_ptr;
DASHTmplId id_type = DASH_TMPL_ID_UNDEFINED;
if (av_strstart(identifier, "$$", &next_ptr)) {
id_type = DASH_TMPL_ID_ESCAPE;
*ptr = next_ptr;
} else if (av_strstart(identifier, "$RepresentationID$", &next_ptr)) {
id_type = DASH_TMPL_ID_REP_ID;
// default to basic format, as $RepresentationID$ identifiers
// are not allowed to have custom format-tags.
av_strlcpy(format_tag, "%d", format_tag_size);
*ptr = next_ptr;
} else { // the following identifiers may have an explicit format_tag
if (av_strstart(identifier, "$Number", &next_ptr))
id_type = DASH_TMPL_ID_NUMBER;
else if (av_strstart(identifier, "$Bandwidth", &next_ptr))
id_type = DASH_TMPL_ID_BANDWIDTH;
else if (av_strstart(identifier, "$Time", &next_ptr))
id_type = DASH_TMPL_ID_TIME;
else
id_type = DASH_TMPL_ID_UNDEFINED;
// next parse the dash format-tag and generate a c-string format tag
// (next_ptr now points at the first '%' at the beginning of the format-tag)
if (id_type != DASH_TMPL_ID_UNDEFINED) {
const char *number_format = DASH_TMPL_ID_TIME ? "lld" : "d";
if (next_ptr[0] == '$') { // no dash format-tag
snprintf(format_tag, format_tag_size, "%%%s", number_format);
*ptr = &next_ptr[1];
} else {
const char *width_ptr;
// only tolerate single-digit width-field (i.e. up to 9-digit width)
if (av_strstart(next_ptr, "%0", &width_ptr) &&
av_isdigit(width_ptr[0]) &&
av_strstart(&width_ptr[1], "d$", &next_ptr)) {
// yes, we're using a format tag to build format_tag.
snprintf(format_tag, format_tag_size, "%s%c%s", "%0", width_ptr[0], number_format);
*ptr = next_ptr;
} else {
av_log(NULL, AV_LOG_WARNING, "Failed to parse format-tag beginning with %s. Expected either a "
"closing '$' character or a format-string like '%%0[width]d', "
"where width must be a single digit\n", next_ptr);
id_type = DASH_TMPL_ID_UNDEFINED;
}
}
}
}
return id_type;
}
static void dash_fill_tmpl_params(char *dst, size_t buffer_size,
const char *template, int rep_id,
int number, int bit_rate,
int64_t time) {
int dst_pos = 0;
const char *t_cur = template;
while (dst_pos < buffer_size - 1 && *t_cur) {
char format_tag[7]; // May be "%d", "%0Xd", or "%0Xlld" (for $Time$), where X is in [0-9]
int n = 0;
DASHTmplId id_type;
const char *t_next = strchr(t_cur, '$'); // copy over everything up to the first '$' character
if (t_next) {
int num_copy_bytes = FFMIN(t_next - t_cur, buffer_size - dst_pos - 1);
av_strlcpy(&dst[dst_pos], t_cur, num_copy_bytes + 1);
// advance
dst_pos += num_copy_bytes;
t_cur = t_next;
} else { // no more DASH identifiers to substitute - just copy the rest over and break
av_strlcpy(&dst[dst_pos], t_cur, buffer_size - dst_pos);
break;
}
if (dst_pos >= buffer_size - 1 || !*t_cur)
break;
// t_cur is now pointing to a '$' character
id_type = dash_read_tmpl_id(t_cur, format_tag, sizeof(format_tag), &t_next);
switch (id_type) {
case DASH_TMPL_ID_ESCAPE:
av_strlcpy(&dst[dst_pos], "$", 2);
n = 1;
break;
case DASH_TMPL_ID_REP_ID:
n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, rep_id);
break;
case DASH_TMPL_ID_NUMBER:
n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, number);
break;
case DASH_TMPL_ID_BANDWIDTH:
n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, bit_rate);
break;
case DASH_TMPL_ID_TIME:
n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, time);
break;
case DASH_TMPL_ID_UNDEFINED:
// copy over one byte and advance
av_strlcpy(&dst[dst_pos], t_cur, 2);
n = 1;
t_next = &t_cur[1];
break;
}
// t_next points just past the processed identifier
// n is the number of bytes that were attempted to be written to dst
// (may have failed to write all because buffer_size).
// advance
dst_pos += FFMIN(n, buffer_size - dst_pos - 1);
t_cur = t_next;
}
}
static char *xmlescape(const char *str) {
int outlen = strlen(str)*3/2 + 6;
char *out = av_realloc(NULL, outlen + 1);
int pos = 0;
if (!out)
return NULL;
for (; *str; str++) {
if (pos + 6 > outlen) {
char *tmp;
outlen = 2 * outlen + 6;
tmp = av_realloc(out, outlen + 1);
if (!tmp) {
av_free(out);
return NULL;
}
out = tmp;
}
if (*str == '&') {
memcpy(&out[pos], "&amp;", 5);
pos += 5;
} else if (*str == '<') {
memcpy(&out[pos], "&lt;", 4);
pos += 4;
} else if (*str == '>') {
memcpy(&out[pos], "&gt;", 4);
pos += 4;
} else if (*str == '\'') {
memcpy(&out[pos], "&apos;", 6);
pos += 6;
} else if (*str == '\"') {
memcpy(&out[pos], "&quot;", 6);
pos += 6;
} else {
out[pos++] = *str;
}
}
out[pos] = '\0';
return out;
}
static void write_time(AVIOContext *out, int64_t time)
{
int seconds = time / AV_TIME_BASE;
int fractions = time % AV_TIME_BASE;
int minutes = seconds / 60;
int hours = minutes / 60;
seconds %= 60;
minutes %= 60;
avio_printf(out, "PT");
if (hours)
avio_printf(out, "%dH", hours);
if (hours || minutes)
avio_printf(out, "%dM", minutes);
avio_printf(out, "%d.%dS", seconds, fractions / (AV_TIME_BASE / 10));
}
static int write_manifest(AVFormatContext *s, int final)
{
DASHContext *c = s->priv_data;
AVIOContext *out;
char temp_filename[1024];
int ret, i;
AVDictionaryEntry *title = av_dict_get(s->metadata, "title", NULL, 0);
snprintf(temp_filename, sizeof(temp_filename), "%s.tmp", s->filename);
ret = avio_open2(&out, temp_filename, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
if (ret < 0) {
av_log(s, AV_LOG_ERROR, "Unable to open %s for writing\n", temp_filename);
return ret;
}
avio_printf(out, "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n");
avio_printf(out, "<MPD xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n"
"\txmlns=\"urn:mpeg:dash:schema:mpd:2011\"\n"
"\txmlns:xlink=\"http://www.w3.org/1999/xlink\"\n"
"\txsi:schemaLocation=\"urn:mpeg:DASH:schema:MPD:2011 http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-DASH_schema_files/DASH-MPD.xsd\"\n"
"\tprofiles=\"urn:mpeg:dash:profile:isoff-live:2011\"\n"
"\ttype=\"%s\"\n", final ? "static" : "dynamic");
if (final) {
avio_printf(out, "\tmediaPresentationDuration=\"");
write_time(out, c->total_duration);
avio_printf(out, "\"\n");
} else {
int64_t update_period = c->last_duration / AV_TIME_BASE;
if (c->use_template && !c->use_timeline)
update_period = 500;
avio_printf(out, "\tminimumUpdatePeriod=\"PT%"PRId64"S\"\n", update_period);
avio_printf(out, "\tsuggestedPresentationDelay=\"PT%"PRId64"S\"\n", c->last_duration / AV_TIME_BASE);
if (!c->availability_start_time[0] && s->nb_streams > 0 && c->streams[0].nb_segments > 0) {
time_t t = time(NULL);
struct tm *ptm, tmbuf;
ptm = gmtime_r(&t, &tmbuf);
if (ptm) {
if (!strftime(c->availability_start_time, sizeof(c->availability_start_time),
"%Y-%m-%dT%H:%M:%S", ptm))
c->availability_start_time[0] = '\0';
}
}
if (c->availability_start_time[0])
avio_printf(out, "\tavailabilityStartTime=\"%s\"\n", c->availability_start_time);
if (c->window_size && c->use_template) {
avio_printf(out, "\ttimeShiftBufferDepth=\"");
write_time(out, c->last_duration * c->window_size);
avio_printf(out, "\"\n");
}
}
avio_printf(out, "\tminBufferTime=\"");
write_time(out, c->last_duration);
avio_printf(out, "\">\n");
avio_printf(out, "\t<ProgramInformation>\n");
if (title) {
char *escaped = xmlescape(title->value);
avio_printf(out, "\t\t<Title>%s</Title>\n", escaped);
av_free(escaped);
}
avio_printf(out, "\t</ProgramInformation>\n");
if (c->window_size && s->nb_streams > 0 && c->streams[0].nb_segments > 0 && !c->use_template) {
OutputStream *os = &c->streams[0];
int start_index = FFMAX(os->nb_segments - c->window_size, 0);
int64_t start_time = av_rescale_q(os->segments[start_index]->time, s->streams[0]->time_base, AV_TIME_BASE_Q);
avio_printf(out, "\t<Period start=\"");
write_time(out, start_time);
avio_printf(out, "\">\n");
} else {
avio_printf(out, "\t<Period start=\"PT0.0S\">\n");
}
if (c->has_video) {
avio_printf(out, "\t\t<AdaptationSet id=\"video\" segmentAlignment=\"true\" bitstreamSwitching=\"true\">\n");
for (i = 0; i < s->nb_streams; i++) {
AVStream *st = s->streams[i];
OutputStream *os = &c->streams[i];
if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_VIDEO)
continue;
avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"video/mp4\" codecs=\"%s\"%s width=\"%d\" height=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codec->width, st->codec->height);
output_segment_list(&c->streams[i], out, c);
avio_printf(out, "\t\t\t</Representation>\n");
}
avio_printf(out, "\t\t</AdaptationSet>\n");
}
if (c->has_audio) {
avio_printf(out, "\t\t<AdaptationSet id=\"audio\" segmentAlignment=\"true\" bitstreamSwitching=\"true\">\n");
for (i = 0; i < s->nb_streams; i++) {
AVStream *st = s->streams[i];
OutputStream *os = &c->streams[i];
if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_AUDIO)
continue;
avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"audio/mp4\" codecs=\"%s\"%s audioSamplingRate=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codec->sample_rate);
avio_printf(out, "\t\t\t\t<AudioChannelConfiguration schemeIdUri=\"urn:mpeg:dash:23003:3:audio_channel_configuration:2011\" value=\"%d\" />\n", st->codec->channels);
output_segment_list(&c->streams[i], out, c);
avio_printf(out, "\t\t\t</Representation>\n");
}
avio_printf(out, "\t\t</AdaptationSet>\n");
}
avio_printf(out, "\t</Period>\n");
avio_printf(out, "</MPD>\n");
avio_flush(out);
avio_close(out);
return ff_rename(temp_filename, s->filename);
}
static int dash_write_header(AVFormatContext *s)
{
DASHContext *c = s->priv_data;
int ret = 0, i;
AVOutputFormat *oformat;
char *ptr;
char basename[1024];
if (c->single_file_name)
c->single_file = 1;
if (c->single_file)
c->use_template = 0;
av_strlcpy(c->dirname, s->filename, sizeof(c->dirname));
ptr = strrchr(c->dirname, '/');
if (ptr) {
av_strlcpy(basename, &ptr[1], sizeof(basename));
ptr[1] = '\0';
} else {
c->dirname[0] = '\0';
av_strlcpy(basename, s->filename, sizeof(basename));
}
ptr = strrchr(basename, '.');
if (ptr)
*ptr = '\0';
oformat = av_guess_format("mp4", NULL, NULL);
if (!oformat) {
ret = AVERROR_MUXER_NOT_FOUND;
goto fail;
}
c->streams = av_mallocz(sizeof(*c->streams) * s->nb_streams);
if (!c->streams) {
ret = AVERROR(ENOMEM);
goto fail;
}
for (i = 0; i < s->nb_streams; i++) {
OutputStream *os = &c->streams[i];
AVFormatContext *ctx;
AVStream *st;
AVDictionary *opts = NULL;
char filename[1024];
os->bit_rate = s->streams[i]->codec->bit_rate;
if (os->bit_rate) {
snprintf(os->bandwidth_str, sizeof(os->bandwidth_str),
" bandwidth=\"%d\"", os->bit_rate);
} else {
int level = s->strict_std_compliance >= FF_COMPLIANCE_STRICT ?
AV_LOG_ERROR : AV_LOG_WARNING;
av_log(s, level, "No bit rate set for stream %d\n", i);
if (s->strict_std_compliance >= FF_COMPLIANCE_STRICT) {
ret = AVERROR(EINVAL);
goto fail;
}
}
ctx = avformat_alloc_context();
if (!ctx) {
ret = AVERROR(ENOMEM);
goto fail;
}
os->ctx = ctx;
ctx->oformat = oformat;
ctx->interrupt_callback = s->interrupt_callback;
if (!(st = avformat_new_stream(ctx, NULL))) {
ret = AVERROR(ENOMEM);
goto fail;
}
avcodec_copy_context(st->codec, s->streams[i]->codec);
st->sample_aspect_ratio = s->streams[i]->sample_aspect_ratio;
st->time_base = s->streams[i]->time_base;
ctx->avoid_negative_ts = s->avoid_negative_ts;
ctx->pb = avio_alloc_context(os->iobuf, sizeof(os->iobuf), AVIO_FLAG_WRITE, os, NULL, dash_write, NULL);
if (!ctx->pb) {
ret = AVERROR(ENOMEM);
goto fail;
}
if (c->single_file) {
if (c->single_file_name)
dash_fill_tmpl_params(os->initfile, sizeof(os->initfile), c->single_file_name, i, 0, os->bit_rate, 0);
else
snprintf(os->initfile, sizeof(os->initfile), "%s-stream%d.m4s", basename, i);
} else {
dash_fill_tmpl_params(os->initfile, sizeof(os->initfile), c->init_seg_name, i, 0, os->bit_rate, 0);
}
snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->initfile);
ret = ffurl_open(&os->out, filename, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
if (ret < 0)
goto fail;
os->init_start_pos = 0;
av_dict_set(&opts, "movflags", "frag_custom+dash", 0);
if ((ret = avformat_write_header(ctx, &opts)) < 0) {
goto fail;
}
os->ctx_inited = 1;
avio_flush(ctx->pb);
av_dict_free(&opts);
if (c->single_file) {
os->init_range_length = avio_tell(ctx->pb);
} else {
ffurl_close(os->out);
os->out = NULL;
}
av_log(s, AV_LOG_VERBOSE, "Representation %d init segment written to: %s\n", i, filename);
s->streams[i]->time_base = st->time_base;
// If the muxer wants to shift timestamps, request to have them shifted
// already before being handed to this muxer, so we don't have mismatches
// between the MPD and the actual segments.
s->avoid_negative_ts = ctx->avoid_negative_ts;
if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO)
c->has_video = 1;
else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO)
c->has_audio = 1;
set_codec_str(s, os->ctx->streams[0]->codec, os->codec_str, sizeof(os->codec_str));
os->first_dts = AV_NOPTS_VALUE;
os->end_dts = AV_NOPTS_VALUE;
os->segment_index = 1;
}
if (!c->has_video && c->min_seg_duration <= 0) {
av_log(s, AV_LOG_WARNING, "no video stream and no min seg duration set\n");
ret = AVERROR(EINVAL);
}
ret = write_manifest(s, 0);
if (!ret)
av_log(s, AV_LOG_VERBOSE, "Manifest written to: %s\n", s->filename);
fail:
if (ret)
dash_free(s);
return ret;
}
static int add_segment(OutputStream *os, const char *file,
int64_t time, int duration,
int64_t start_pos, int64_t range_length,
int64_t index_length)
{
int err;
Segment *seg;
if (os->nb_segments >= os->segments_size) {
os->segments_size = (os->segments_size + 1) * 2;
if ((err = av_reallocp(&os->segments, sizeof(*os->segments) *
os->segments_size)) < 0) {
os->segments_size = 0;
os->nb_segments = 0;
return err;
}
}
seg = av_mallocz(sizeof(*seg));
if (!seg)
return AVERROR(ENOMEM);
av_strlcpy(seg->file, file, sizeof(seg->file));
seg->time = time;
seg->duration = duration;
seg->start_pos = start_pos;
seg->range_length = range_length;
seg->index_length = index_length;
os->segments[os->nb_segments++] = seg;
os->segment_index++;
return 0;
}
static void write_styp(AVIOContext *pb)
{
avio_wb32(pb, 24);
ffio_wfourcc(pb, "styp");
ffio_wfourcc(pb, "msdh");
avio_wb32(pb, 0); /* minor */
ffio_wfourcc(pb, "msdh");
ffio_wfourcc(pb, "msix");
}
static void find_index_range(AVFormatContext *s, const char *full_path,
int64_t pos, int *index_length)
{
uint8_t buf[8];
URLContext *fd;
int ret;
ret = ffurl_open(&fd, full_path, AVIO_FLAG_READ, &s->interrupt_callback, NULL);
if (ret < 0)
return;
if (ffurl_seek(fd, pos, SEEK_SET) != pos) {
ffurl_close(fd);
return;
}
ret = ffurl_read(fd, buf, 8);
ffurl_close(fd);
if (ret < 8)
return;
if (AV_RL32(&buf[4]) != MKTAG('s', 'i', 'd', 'x'))
return;
*index_length = AV_RB32(&buf[0]);
}
static int dash_flush(AVFormatContext *s, int final, int stream)
{
DASHContext *c = s->priv_data;
int i, ret = 0;
int cur_flush_segment_index = 0;
if (stream >= 0)
cur_flush_segment_index = c->streams[stream].segment_index;
for (i = 0; i < s->nb_streams; i++) {
OutputStream *os = &c->streams[i];
char filename[1024] = "", full_path[1024], temp_path[1024];
int64_t start_pos = avio_tell(os->ctx->pb);
int range_length, index_length = 0;
if (!os->packets_written)
continue;
// Flush the single stream that got a keyframe right now.
// Flush all audio streams as well, in sync with video keyframes,
// but not the other video streams.
if (stream >= 0 && i != stream) {
if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_AUDIO)
continue;
// Make sure we don't flush audio streams multiple times, when
// all video streams are flushed one at a time.
if (c->has_video && os->segment_index > cur_flush_segment_index)
continue;
}
if (!c->single_file) {
dash_fill_tmpl_params(filename, sizeof(filename), c->media_seg_name, i, os->segment_index, os->bit_rate, os->start_dts);
snprintf(full_path, sizeof(full_path), "%s%s", c->dirname, filename);
snprintf(temp_path, sizeof(temp_path), "%s.tmp", full_path);
ret = ffurl_open(&os->out, temp_path, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
if (ret < 0)
break;
write_styp(os->ctx->pb);
} else {
snprintf(full_path, sizeof(full_path), "%s%s", c->dirname, os->initfile);
}
av_write_frame(os->ctx, NULL);
avio_flush(os->ctx->pb);
os->packets_written = 0;
range_length = avio_tell(os->ctx->pb) - start_pos;
if (c->single_file) {
find_index_range(s, full_path, start_pos, &index_length);
} else {
ffurl_close(os->out);
os->out = NULL;
ret = ff_rename(temp_path, full_path);
if (ret < 0)
break;
}
add_segment(os, filename, os->start_dts, os->end_dts - os->start_dts, start_pos, range_length, index_length);
av_log(s, AV_LOG_VERBOSE, "Representation %d media segment %d written to: %s\n", i, os->segment_index, full_path);
}
if (c->window_size || (final && c->remove_at_exit)) {
for (i = 0; i < s->nb_streams; i++) {
OutputStream *os = &c->streams[i];
int j;
int remove = os->nb_segments - c->window_size - c->extra_window_size;
if (final && c->remove_at_exit)
remove = os->nb_segments;
if (remove > 0) {
for (j = 0; j < remove; j++) {
char filename[1024];
snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->segments[j]->file);
unlink(filename);
av_free(os->segments[j]);
}
os->nb_segments -= remove;
memmove(os->segments, os->segments + remove, os->nb_segments * sizeof(*os->segments));
}
}
}
if (ret >= 0)
ret = write_manifest(s, final);
return ret;
}
static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
{
DASHContext *c = s->priv_data;
AVStream *st = s->streams[pkt->stream_index];
OutputStream *os = &c->streams[pkt->stream_index];
int64_t seg_end_duration = (os->segment_index) * (int64_t) c->min_seg_duration;
int ret;
// If forcing the stream to start at 0, the mp4 muxer will set the start
// timestamps to 0. Do the same here, to avoid mismatches in duration/timestamps.
if (os->first_dts == AV_NOPTS_VALUE &&
s->avoid_negative_ts == AVFMT_AVOID_NEG_TS_MAKE_ZERO) {
pkt->pts -= pkt->dts;
pkt->dts = 0;
}
if (os->first_dts == AV_NOPTS_VALUE)
os->first_dts = pkt->dts;
if ((!c->has_video || st->codec->codec_type == AVMEDIA_TYPE_VIDEO) &&
pkt->flags & AV_PKT_FLAG_KEY && os->packets_written &&
av_compare_ts(pkt->dts - os->first_dts, st->time_base,
seg_end_duration, AV_TIME_BASE_Q) >= 0) {
int64_t prev_duration = c->last_duration;
c->last_duration = av_rescale_q(pkt->dts - os->start_dts,
st->time_base,
AV_TIME_BASE_Q);
c->total_duration = av_rescale_q(pkt->dts - os->first_dts,
st->time_base,
AV_TIME_BASE_Q);
if ((!c->use_timeline || !c->use_template) && prev_duration) {
if (c->last_duration < prev_duration*9/10 ||
c->last_duration > prev_duration*11/10) {
av_log(s, AV_LOG_WARNING,
"Segment durations differ too much, enable use_timeline "
"and use_template, or keep a stricter keyframe interval\n");
}
}
if ((ret = dash_flush(s, 0, pkt->stream_index)) < 0)
return ret;
}
if (!os->packets_written) {
// If we wrote a previous segment, adjust the start time of the segment
// to the end of the previous one (which is the same as the mp4 muxer
// does). This avoids gaps in the timeline.
if (os->end_dts != AV_NOPTS_VALUE)
os->start_dts = os->end_dts;
else
os->start_dts = pkt->dts;
}
os->end_dts = pkt->dts + pkt->duration;
os->packets_written++;
return ff_write_chained(os->ctx, 0, pkt, s);
}
static int dash_write_trailer(AVFormatContext *s)
{
DASHContext *c = s->priv_data;
if (s->nb_streams > 0) {
OutputStream *os = &c->streams[0];
// If no segments have been written so far, try to do a crude
// guess of the segment duration
if (!c->last_duration)
c->last_duration = av_rescale_q(os->end_dts - os->start_dts,
s->streams[0]->time_base,
AV_TIME_BASE_Q);
c->total_duration = av_rescale_q(os->end_dts - os->first_dts,
s->streams[0]->time_base,
AV_TIME_BASE_Q);
}
dash_flush(s, 1, -1);
if (c->remove_at_exit) {
char filename[1024];
int i;
for (i = 0; i < s->nb_streams; i++) {
OutputStream *os = &c->streams[i];
snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->initfile);
unlink(filename);
}
unlink(s->filename);
}
dash_free(s);
return 0;
}
#define OFFSET(x) offsetof(DASHContext, x)
#define E AV_OPT_FLAG_ENCODING_PARAM
static const AVOption options[] = {
{ "window_size", "number of segments kept in the manifest", OFFSET(window_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, E },
{ "extra_window_size", "number of segments kept outside of the manifest before removing from disk", OFFSET(extra_window_size), AV_OPT_TYPE_INT, { .i64 = 5 }, 0, INT_MAX, E },
{ "min_seg_duration", "minimum segment duration (in microseconds)", OFFSET(min_seg_duration), AV_OPT_TYPE_INT64, { .i64 = 5000000 }, 0, INT_MAX, E },
{ "remove_at_exit", "remove all segments when finished", OFFSET(remove_at_exit), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, E },
{ "use_template", "Use SegmentTemplate instead of SegmentList", OFFSET(use_template), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, E },
{ "use_timeline", "Use SegmentTimeline in SegmentTemplate", OFFSET(use_timeline), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, E },
{ "single_file", "Store all segments in one file, accessed using byte ranges", OFFSET(single_file), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, E },
{ "single_file_name", "DASH-templated name to be used for baseURL. Implies storing all segments in one file, accessed using byte ranges", OFFSET(single_file_name), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, E },
{ "init_seg_name", "DASH-templated name to used for the initialization segment", OFFSET(init_seg_name), AV_OPT_TYPE_STRING, {.str = "init-stream$RepresentationID$.m4s"}, 0, 0, E },
{ "media_seg_name", "DASH-templated name to used for the media segments", OFFSET(media_seg_name), AV_OPT_TYPE_STRING, {.str = "chunk-stream$RepresentationID$-$Number%05d$.m4s"}, 0, 0, E },
{ NULL },
};
static const AVClass dash_class = {
.class_name = "dash muxer",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
AVOutputFormat ff_dash_muxer = {
.name = "dash",
.long_name = NULL_IF_CONFIG_SMALL("DASH Muxer"),
.priv_data_size = sizeof(DASHContext),
.audio_codec = AV_CODEC_ID_AAC,
.video_codec = AV_CODEC_ID_H264,
.flags = AVFMT_GLOBALHEADER | AVFMT_NOFILE | AVFMT_TS_NEGATIVE,
.write_header = dash_write_header,
.write_packet = dash_write_packet,
.write_trailer = dash_write_trailer,
.codec_tag = (const AVCodecTag* const []){ ff_mp4_obj_type, 0 },
.priv_class = &dash_class,
};
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