[FFmpeg-devel] [PATCH 2/2] lavf: Add WebM DASH Manifest Muxer

Timothy Gu timothygu99 at gmail.com
Tue Jul 1 01:26:59 CEST 2014


On Mon, Jun 30, 2014 at 3:44 PM, Vignesh Venkatasubramanian
<vigneshv at google.com> wrote:

> diff --git a/Changelog b/Changelog
> index 0346877..81ae8ab 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -30,6 +30,7 @@ version <next>:
>  - zoompan filter
>  - signalstats filter
>  - hqx filter (hq2x, hq3x, hq4x)
> +- WebM DASH Manifest

WebM DASH Manifest muxer

> diff --git a/libavformat/webmdashenc.c b/libavformat/webmdashenc.c
> new file mode 100644
> index 0000000..d8c2a65
> --- /dev/null
> +++ b/libavformat/webmdashenc.c
> @@ -0,0 +1,306 @@
> +/*
> + * WebM DASH Manifest XML muxer
> + * Copyright (c) 2014 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
> + */
> +
> +/*
> + * WebM DASH Specification:
> + * https://sites.google.com/a/webmproject.org/wiki/adaptive-streaming/webm-dash-specification
> + */
> +
> +#include <stdint.h>
> +#include <string.h>
> +
> +#include "avformat.h"
> +#include "avio_internal.h"
> +#include "matroska.h"
> +
> +#include "libavutil/avstring.h"
> +#include "libavutil/dict.h"
> +#include "libavutil/opt.h"
> +
> +typedef struct AdaptationSet {
> +    char id[10];
> +    int *streams;
> +    int nb_streams;
> +} AdaptationSet;
> +
> +typedef struct WebMDashMuxContext {
> +    const AVClass  *class;
> +    char *adaptation_sets;
> +    AdaptationSet *as;
> +    int nb_as;
> +} WebMDashMuxContext;
> +
> +static void write_string(AVFormatContext *s, const char *str, int should_free)
> +{
> +    avio_write(s->pb, str, strlen(str));
> +    if (should_free)
> +        av_free((char*)str);
> +}
> +
> +static const char *get_codec_name(int codec_id)
> +{
> +    switch (codec_id) {
> +        case AV_CODEC_ID_VP8:
> +            return "vp8";
> +        case AV_CODEC_ID_VP9:
> +            return "vp9";
> +        case AV_CODEC_ID_VORBIS:
> +            return "vorbis";
> +        case AV_CODEC_ID_OPUS:
> +            return "opus";
> +    }
> +    return NULL;
> +}
> +
> +static double get_duration(AVFormatContext *s)
> +{
> +    int i = 0;
> +    double max = 0.0;
> +    for (i = 0; i < s->nb_streams; i++) {
> +        AVDictionaryEntry *duration = av_dict_get(s->streams[i]->metadata,
> +                                                  DURATION, NULL, 0);
> +        if (atof(duration->value) > max) max = atof(duration->value);
> +    }
> +    return max / 1000;
> +}
> +
> +static void write_header(AVFormatContext *s)
> +{
> +    double min_buffer_time = 1.0;
> +    write_string(s, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n", 0);
> +    write_string(s, "<MPD\n", 0);
> +    write_string(s, "  xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n", 0);
> +    write_string(s, "  xmlns=\"urn:mpeg:DASH:schema:MPD:2011\"\n", 0);
> +    write_string(s, "  xsi:schemaLocation=\"urn:mpeg:DASH:schema:MPD:2011\"\n", 0);
> +    write_string(s, "  type=\"static\"\n", 0);
> +    write_string(s, av_asprintf("  mediaPresentationDuration=\"PT%gS\"\n", get_duration(s)), 1);
> +    write_string(s, av_asprintf("  minBufferTime=\"PT%gS\"\n", min_buffer_time), 1);
> +    write_string(s, "  profiles=\"urn:webm:dash:profile:webm-on-demand:2012\"", 0);
> +    write_string(s, ">\n", 0);
> +}
> +
> +static void write_footer(AVFormatContext *s)
> +{
> +    write_string(s, "</MPD>", 0);
> +}
> +
> +static int subsegment_alignment(AVFormatContext *s, AdaptationSet *as) {
> +    int i;
> +    AVDictionaryEntry *gold = av_dict_get(s->streams[as->streams[0]]->metadata,
> +                                          CUE_TIMESTAMPS, NULL, 0);
> +    for (i = 1; i < as->nb_streams; i++) {
> +        AVDictionaryEntry *ts = av_dict_get(s->streams[as->streams[i]]->metadata,
> +                                            CUE_TIMESTAMPS, NULL, 0);
> +        if (strncmp(gold->value, ts->value, strlen(gold->value))) return 0;
> +    }
> +    return 1;
> +}
> +
> +static int bitstream_switching(AVFormatContext *s, AdaptationSet *as) {
> +    int i;
> +    AVDictionaryEntry *gold_track_num = av_dict_get(s->streams[as->streams[0]]->metadata,
> +                                                    TRACK_NUMBER, NULL, 0);
> +    AVCodecContext *gold_codec = s->streams[as->streams[0]]->codec;
> +    for (i = 1; i < as->nb_streams; i++) {
> +        AVDictionaryEntry *track_num = av_dict_get(s->streams[as->streams[i]]->metadata,
> +                                                   TRACK_NUMBER, NULL, 0);
> +        AVCodecContext *codec = s->streams[as->streams[i]]->codec;
> +        if (strncmp(gold_track_num->value, track_num->value, strlen(gold_track_num->value)) ||
> +            gold_codec->codec_id != codec->codec_id ||
> +            gold_codec->extradata_size != codec->extradata_size ||
> +            memcmp(gold_codec->extradata, codec->extradata, codec->extradata_size)) {
> +            return 0;
> +        }
> +    }
> +    return 1;
> +}
> +
> +static void write_adaptation_set(AVFormatContext *s, int as_index)
> +{
> +    WebMDashMuxContext *w = s->priv_data;
> +    AdaptationSet *as = &w->as[as_index];
> +    AVCodecContext *codec = s->streams[as->streams[0]]->codec;
> +    int i;
> +    char boolean[2][6] = { "false", "true" };
> +    int subsegmentStartsWithSAP = 1;
> +    AVDictionaryEntry *lang;
> +    write_string(s, av_asprintf("<AdaptationSet id=\"%s\"", as->id), 1);
> +    write_string(s, av_asprintf(" mimeType=\"%s/webm\"",
> +                                codec->codec_type == AVMEDIA_TYPE_VIDEO ? "video" : "audio"), 1);
> +    write_string(s, av_asprintf(" codecs=\"%s\"", get_codec_name(codec->codec_id)), 1);
> +
> +    lang = av_dict_get(s->streams[as->streams[0]]->metadata, "language", NULL, 0);
> +    if (lang != NULL) write_string(s, av_asprintf(" lang=\"%s\"", lang->value), 1);
> +
> +    if (codec->codec_type == AVMEDIA_TYPE_VIDEO) {
> +        write_string(s, av_asprintf(" width=\"%d\"", codec->width), 1);
> +        write_string(s, av_asprintf(" height=\"%d\"", codec->height), 1);
> +    } else {
> +        write_string(s, av_asprintf(" audioSamplingRate=\"%d\"", codec->sample_rate), 1);
> +    }
> +
> +    write_string(s, av_asprintf(" bitstreamSwitching=\"%s\"", boolean[bitstream_switching(s, as)]), 1);
> +    write_string(s, av_asprintf(" subsegmentAlignment=\"%s\"", boolean[subsegment_alignment(s, as)]), 1);
> +
> +    for (i = 0; i < as->nb_streams; i++) {
> +        AVDictionaryEntry *kf = av_dict_get(s->streams[as->streams[i]]->metadata,
> +                                            CLUSTER_KEYFRAME, NULL, 0);
> +        if (!strncmp(kf->value, "0", 1)) subsegmentStartsWithSAP = 0;
> +    }
> +    write_string(s, av_asprintf(" subsegmentStartsWithSAP=\"%d\"", subsegmentStartsWithSAP), 1);
> +    write_string(s, ">\n", 0);
> +
> +    for (i = 0; i < as->nb_streams; i++) {
> +        AVStream *stream = s->streams[as->streams[i]];
> +        AVDictionaryEntry *irange = av_dict_get(stream->metadata, INITIALIZATION_RANGE, NULL, 0);
> +        AVDictionaryEntry *cues_start = av_dict_get(stream->metadata, CUES_START, NULL, 0);
> +        AVDictionaryEntry *cues_end = av_dict_get(stream->metadata, CUES_END, NULL, 0);
> +        AVDictionaryEntry *filename = av_dict_get(stream->metadata, FILENAME, NULL, 0);
> +        AVDictionaryEntry *bandwidth = av_dict_get(stream->metadata, BANDWIDTH, NULL, 0);
> +        write_string(s, av_asprintf("<Representation id=\"%d\"", i), 1);
> +        write_string(s, av_asprintf(" bandwidth=\"%s\"", bandwidth->value), 1);
> +        write_string(s, ">\n", 0);
> +        write_string(s, av_asprintf("<BaseURL>%s</BaseURL>\n", filename->value), 1);
> +        write_string(s, "<SegmentBase\n", 0);
> +        write_string(s, av_asprintf("  indexRange=\"%s-%s\">\n", cues_start->value, cues_end->value), 1);
> +        write_string(s, "<Initialization\n", 0);
> +        write_string(s, av_asprintf("  range=\"0-%s\" />\n", irange->value), 1);
> +        write_string(s, "</SegmentBase>\n", 0);
> +        write_string(s, "</Representation>\n", 0);
> +    }
> +    write_string(s, "</AdaptationSet>\n", 0);
> +}
> +
> +static int to_integer(char *p, int len)
> +{
> +    int ret;
> +    char *q = (char*)av_malloc(sizeof(char) * len);
> +    strncpy(q, p, len);
> +    ret = atoi(q);
> +    av_free(q);
> +    return ret;
> +}
> +
> +static int parse_adaptation_sets(AVFormatContext *s)
> +{
> +    WebMDashMuxContext *w = s->priv_data;
> +    char *p = w->adaptation_sets;
> +    char *q;
> +    enum { new_set, parsed_id, parsing_streams } state;
> +    // syntax id=0,streams=0,1,2 id=1,streams=3,4 and so on
> +    state = new_set;
> +    while (p < w->adaptation_sets + strlen(w->adaptation_sets)) {
> +        if (*p == ' ')
> +            continue;
> +        else if (state == new_set && !strncmp(p, "id=", 3)) {
> +            w->as = av_realloc(w->as, sizeof(*w->as) * ++w->nb_as);
> +            w->as[w->nb_as - 1].nb_streams = 0;
> +            w->as[w->nb_as - 1].streams = NULL;
> +            p += 3; // consume "id="
> +            q = w->as[w->nb_as - 1].id;
> +            while (*p != ',') *q++ = *p++;
> +            *q = 0;
> +            p++;
> +            state = parsed_id;
> +        } else if (state == parsed_id && !strncmp(p, "streams=", 8)) {
> +            p += 8; // consume "streams="
> +            state = parsing_streams;
> +        } else if (state == parsing_streams) {
> +            struct AdaptationSet *as = &w->as[w->nb_as - 1];
> +            q = p;
> +            while (*q != '\0' && *q != ',' && *q != ' ') q++;
> +            as->streams = av_realloc(as->streams, sizeof(*as->streams) * ++as->nb_streams);
> +            as->streams[as->nb_streams - 1] = to_integer(p, q - p);
> +            if (*q == '\0') break;
> +            if (*q == ' ') state = new_set;
> +            p = ++q;
> +        } else {
> +            return -1;
> +        }
> +    }
> +    return 0;
> +}
> +
> +static int webm_dash_manifest_write_header(AVFormatContext *s)
> +{
> +    int i;
> +    double start = 0.0;
> +    WebMDashMuxContext *w = s->priv_data;
> +    parse_adaptation_sets(s);
> +    write_header(s);
> +    write_string(s, "<Period id=\"0\"", 0);
> +    write_string(s, av_asprintf(" start=\"PT%gS\"", start), 1);
> +    write_string(s, av_asprintf(" duration=\"PT%gS\"", get_duration(s)), 1);
> +    write_string(s, " >\n", 0);
> +
> +    for (i = 0; i < w->nb_as; i++) {
> +        write_adaptation_set(s, i);
> +    }
> +
> +    write_string(s, "</Period>\n", 0);
> +    write_footer(s);
> +    return 0;
> +}
> +
> +static int webm_dash_manifest_write_packet(AVFormatContext *s, AVPacket *pkt)
> +{
> +    return 0;
> +}
> +
> +static int webm_dash_manifest_write_trailer(AVFormatContext *s)
> +{
> +    WebMDashMuxContext *w = s->priv_data;
> +    int i;
> +    for (i = 0; i < w->nb_as; i++) {
> +        av_free(w->as[i].streams);
> +    }
> +    av_free(w->as);
> +    return 0;
> +}
> +
> +#define OFFSET(x) offsetof(WebMDashMuxContext, x)
> +static const AVOption options[] = {
> +    { "adaptation_sets", "Adaptation sets. Syntax id=0,streams=0,1,2 id=1 streams=3,4 and so on",
> OFFSET(adaptation_sets), AV_OPT_TYPE_STRING, { 0 }, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },

I don't get the help message. Is it supposed to be:
"id=0,streams=0,1,2 id=1,streams=3,4"
or "id=0 streams=0,1,2 id=1 streams=3,4"?

Also this needs an doc/muxers.texi update, preferably with some
real-world examples.

> +    { NULL },
> +};
> +
> +#if CONFIG_WEBM_DASH_MANIFEST_MUXER
> +static const AVClass webm_dash_class = {
> +    .class_name = "webm dash manifest muxer",

Proper capitalization: WebM DASH Manifest muxer

> +    .item_name  = av_default_item_name,
> +    .option     = options,
> +    .version    = LIBAVUTIL_VERSION_INT,
> +};
> +
> +AVOutputFormat ff_webm_dash_manifest_muxer = {
> +    .name              = "webm_dash_manifest",
> +    .long_name         = NULL_IF_CONFIG_SMALL("WebM DASH Manifest"),
> +    .mime_type         = "application/xml",
> +    .extensions        = "xml",
> +    .priv_data_size    = sizeof(WebMDashMuxContext),

> +    .audio_codec       = AV_CODEC_ID_VORBIS || AV_CODEC_ID_OPUS,
> +    .video_codec       = AV_CODEC_ID_VP8 || AV_CODEC_ID_VP9,

I don't think this will work. audio_ and video_codec are for default
codecs. I'm not 100% sure what to do if what you want is "valid
codecs", writing a query_codec callback maybe?

> +    .write_header      = webm_dash_manifest_write_header,
> +    .write_packet      = webm_dash_manifest_write_packet,
> +    .write_trailer     = webm_dash_manifest_write_trailer,
> +    .priv_class        = &webm_dash_class,
> +};
> +#endif
> --
> 2.0.0.526.g5318336
>
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