[FFmpeg-devel] [PATCH] lavf: Add support for WebM Live Muxing

[Michael Niedermayer]

On Mon, Mar 30, 2015 at 02:46:10PM -0700, Vignesh Venkatasubramanian wrote:
> This patch adds support for WebM Live Muxing by adding a new WebM
> Chunk muxer. It writes out live WebM Chunks which can be used for
> playback using Live DASH Clients.
> 
> Please see muxers.texi for sample usage.

[...]

> diff --git a/libavformat/version.h b/libavformat/version.h
> index a183d7f..ff85227 100644
> --- a/libavformat/version.h
> +++ b/libavformat/version.h
> @@ -30,7 +30,7 @@
>  #include "libavutil/version.h"
>  
>  #define LIBAVFORMAT_VERSION_MAJOR 56
> -#define LIBAVFORMAT_VERSION_MINOR  26
> +#define LIBAVFORMAT_VERSION_MINOR  27
>  #define LIBAVFORMAT_VERSION_MICRO 101
>  
>  #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
> diff --git a/libavformat/webm_chunk.c b/libavformat/webm_chunk.c
> new file mode 100644
> index 0000000..48ea6f0
> --- /dev/null
> +++ b/libavformat/webm_chunk.c
> @@ -0,0 +1,262 @@
> +/*
> + * 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 <float.h>
> +#include <time.h>
> +
> +#include "avformat.h"
> +#include "avio.h"
> +#include "internal.h"
> +
> +#include "libavutil/avassert.h"
> +#include "libavutil/log.h"
> +#include "libavutil/opt.h"
> +#include "libavutil/avstring.h"
> +#include "libavutil/parseutils.h"
> +#include "libavutil/mathematics.h"
> +#include "libavutil/time.h"
> +#include "libavutil/time_internal.h"
> +#include "libavutil/timestamp.h"
> +
> +typedef struct WebMChunkContext {
> +    const AVClass *class;
> +    int chunk_start_index;
> +    char *header_filename;
> +    int chunk_duration;
> +    int chunk_count;
> +    int chunk_index;
> +    uint64_t duration_written;
> +    int prev_pts;
> +    AVOutputFormat *oformat;
> +    AVFormatContext *avf;
> +} WebMChunkContext;
> +
> +static int chunk_mux_init(AVFormatContext *s)
> +{
> +    WebMChunkContext *wc = s->priv_data;
> +    AVFormatContext *oc;
> +    int ret;
> +
> +    ret = avformat_alloc_output_context2(&wc->avf, wc->oformat, NULL, NULL);
> +    if (ret < 0)
> +        return ret;
> +    oc = wc->avf;
> +
> +    oc->interrupt_callback = s->interrupt_callback;
> +    oc->max_delay          = s->max_delay;
> +    av_dict_copy(&oc->metadata, s->metadata, 0);
> +
> +    oc->priv_data = av_mallocz(oc->oformat->priv_data_size);
> +    if (!oc->priv_data) {
> +        avio_close(oc->pb);
> +        return AVERROR(ENOMEM);
> +    }
> +    *(const AVClass**)oc->priv_data = oc->oformat->priv_class;
> +    av_opt_set_defaults(oc->priv_data);
> +    av_opt_set_int(oc->priv_data, "dash", 1, 0);
> +    av_opt_set_int(oc->priv_data, "cluster_time_limit", wc->chunk_duration, 0);
> +    av_opt_set_int(oc->priv_data, "live", 1, 0);
> +

> +    oc->streams = s->streams;
> +    oc->nb_streams = s->nb_streams;

why doesnt the code use avformat_new_stream() and avcodec_copy_context()
see hlsenc/segment muxers for examples

or is there a reason why this would not work or be hard ?

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Concerning the gods, I have no means of knowing whether they exist or not
or of what sort they may be, because of the obscurity of the subject, and
the brevity of human life -- Protagoras
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