[FFmpeg-devel] [PATCH] add ivf muxer

[Tomas Härdin]

On Mon, 2010-12-13 at 20:44 +0100, Reimar D?ffinger wrote:
> Hello,
> this is useful for creating VP8 test-cases and/or testing of some
> VP8 decoders.
> Comments?
> 
> snip
> Index: libavformat/ivfenc.c
> ===================================================================
> --- libavformat/ivfenc.c        (revision 0)
> +++ libavformat/ivfenc.c        (revision 0)
> @@ -0,0 +1,71 @@
> +/*
> + * Copyright (c) 2010 Reimar D?ffinger
> + *
> + * 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 "avformat.h"
> +#include "libavutil/intreadwrite.h"
> +
> +static int ivf_write_header(AVFormatContext *s)
> +{
> +    AVCodecContext *ctx;
> +    ByteIOContext *pb = s->pb;
> +
> +    if (s->nb_streams != 1) {
> +        av_log(s, AV_LOG_ERROR, "Format supports only exactly one
> video stream\n");

"only supports" is perhaps more gramatically correct?

> +        return AVERROR(EINVAL);
> +    }
> +    ctx = s->streams[0]->codec;
> +    if (ctx->codec_type != CODEC_TYPE_VIDEO || ctx->codec_id !=
> CODEC_ID_VP8) {
> +        av_log(s, AV_LOG_ERROR, "Currently only VP8 is supported!
> \n");

Does IVF support any other formats at all? Is there a spec?
The demuxer seems to imply that there's support for all AVI FOURCCs, but
maybe that's just code sharing and being a little tolerant. 

> +        return AVERROR(EINVAL);
> +    }
> +    put_buffer(pb, "DKIF", 4);
> +    put_le16(pb, 0); // version
> +    put_le16(pb, 32); // header length
> +    put_le32(pb, ctx->codec_tag ? ctx->codec_tag : AV_RL32("VP80"));
> +    put_le16(pb, ctx->width);
> +    put_le16(pb, ctx->height);
> +    put_le32(pb, s->streams[0]->time_base.den);
> +    put_le32(pb, s->streams[0]->time_base.num);
> +    put_le64(pb, s->streams[0]->duration); // TODO: duration or
> number of frames?!?

This sort of depends on whether VP8/IVF supports VFR, right? The demuxer
doesn't give many hints, but with CFR you'll have duration == number of
frames. Hm.

> +    return 0;
> +}
> +
> +static int ivf_write_packet(AVFormatContext *s, AVPacket *pkt)
> +{
> +    ByteIOContext *pb = s->pb;
> +    put_le32(pb, pkt->size);
> +    put_le64(pb, pkt->pts);
> +    put_buffer(pb, pkt->data, pkt->size);
> +    put_flush_packet(pb);
> +
> +    return 0;
> +}
> +
> +AVOutputFormat ivf_muxer = {
> +    "ivf",
> +    NULL_IF_CONFIG_SMALL("On2 IVF"),
> +    "",
> +    "ivf",
> +    0,
> +    CODEC_ID_NONE,
> +    CODEC_ID_VP8,
> +    ivf_write_header,
> +    ivf_write_packet,

Use named initializers for all of these?

> +};

Maybe add some documentation, and a Changelog entry,

/Tomas
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