/*
* webp muxer
* Copyright (c) 2014 Michael Niedermayer
*
* 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 "libavutil/intreadwrite.h"
#include "libavutil/opt.h"
#include "avformat.h"
#include "internal.h"
typedef struct WebpContext{
AVClass *class;
int frame_count;
AVPacket last_pkt;
int loop;
int wrote_webp_header;
int using_webp_anim_encoder;
} WebpContext;
static int webp_write_header(AVFormatContext *s)
{
AVStream *st;
if (s->nb_streams != 1) {
av_log(s, AV_LOG_ERROR, "Only exactly 1 stream is supported\n");
return AVERROR(EINVAL);
}
st = s->streams[0];
if (st->codecpar->codec_id != AV_CODEC_ID_WEBP) {
av_log(s, AV_LOG_ERROR, "Only WebP is supported\n");
return AVERROR(EINVAL);
}
avpriv_set_pts_info(st, 24, 1, 1000);
return 0;
}
static int is_animated_webp_packet(AVPacket *pkt)
{
if (pkt->size) {
int skip = 0;
unsigned flags = 0;
if (pkt->size < 4)
return 0;
if (AV_RL32(pkt->data) == AV_RL32("RIFF"))
skip = 12;
if (pkt->size < skip + 4)
return 0;
if (AV_RL32(pkt->data + skip) == AV_RL32("VP8X")) {
flags |= pkt->data[skip + 4 + 4];
}
if (flags & 2) // ANIMATION_FLAG is on
return 1;
}
return 0;
}
static int flush(AVFormatContext *s, int trailer, int64_t pts)
{
WebpContext *w = s->priv_data;
AVStream *st = s->streams[0];
if (w->last_pkt.size) {
int skip = 0;
unsigned flags = 0;
int vp8x = 0;
if (w->last_pkt.size < 4)
return 0;
if (AV_RL32(w->last_pkt.data) == AV_RL32("RIFF"))
skip = 12;
if (w->last_pkt.size < skip + 4)
return 0; // Safe to do this as a valid WebP bitstream is >=30 bytes.
if (AV_RL32(w->last_pkt.data + skip) == AV_RL32("VP8X")) {
flags |= w->last_pkt.data[skip + 4 + 4];
vp8x = 1;
skip += AV_RL32(w->last_pkt.data + skip + 4) + 8;
}
if (!w->wrote_webp_header) {
avio_write(s->pb, "RIFF\0\0\0\0WEBP", 12);
w->wrote_webp_header = 1;
if (w->frame_count > 1) // first non-empty packet
w->frame_count = 1; // so we don't count previous empty packets.
}
if (w->frame_count == 1) {
if (!trailer) {
vp8x = 1;
flags |= 2 + 16;
}
if (vp8x) {
avio_write(s->pb, "VP8X", 4);
avio_wl32(s->pb, 10);
avio_w8(s->pb, flags);
avio_wl24(s->pb, 0);
avio_wl24(s->pb, st->codecpar->width - 1);
avio_wl24(s->pb, st->codecpar->height - 1);
}
if (!trailer) {
avio_write(s->pb, "ANIM", 4);
avio_wl32(s->pb, 6);
avio_wl32(s->pb, 0xFFFFFFFF);
avio_wl16(s->pb, w->loop);
}
}
if (w->frame_count > trailer) {
avio_write(s->pb, "ANMF", 4);
avio_wl32(s->pb, 16 + w->last_pkt.size - skip);
avio_wl24(s->pb, 0);
avio_wl24(s->pb, 0);
avio_wl24(s->pb, st->codecpar->width - 1);
avio_wl24(s->pb, st->codecpar->height - 1);
if (w->last_pkt.pts != AV_NOPTS_VALUE && pts != AV_NOPTS_VALUE) {
avio_wl24(s->pb, pts - w->last_pkt.pts);
} else
avio_wl24(s->pb, w->last_pkt.duration);
avio_w8(s->pb, 0);
}
avio_write(s->pb, w->last_pkt.data + skip, w->last_pkt.size - skip);
av_packet_unref(&w->last_pkt);
}
return 0;
}
static int webp_write_packet(AVFormatContext *s, AVPacket *pkt)
{
WebpContext *w = s->priv_data;
w->using_webp_anim_encoder |= is_animated_webp_packet(pkt);
if (w->using_webp_anim_encoder) {
avio_write(s->pb, pkt->data, pkt->size);
w->wrote_webp_header = 1; // for good measure
} else {
int ret;
if ((ret = flush(s, 0, pkt->pts)) < 0)
return ret;
av_packet_ref(&w->last_pkt, pkt);
}
++w->frame_count;
return 0;
}
static int webp_write_trailer(AVFormatContext *s)
{
unsigned filesize;
WebpContext *w = s->priv_data;
if (w->using_webp_anim_encoder) {
if ((w->frame_count > 1) && w->loop) { // Write loop count.
avio_seek(s->pb, 42, SEEK_SET);
avio_wl16(s->pb, w->loop);
}
} else {
int ret;
if ((ret = flush(s, 1, AV_NOPTS_VALUE)) < 0)
return ret;
filesize = avio_tell(s->pb);
avio_seek(s->pb, 4, SEEK_SET);
avio_wl32(s->pb, filesize - 8);
// Note: without the following, avio only writes 8 bytes to the file.
avio_seek(s->pb, filesize, SEEK_SET);
}
return 0;
}
#define OFFSET(x) offsetof(WebpContext, x)
#define ENC AV_OPT_FLAG_ENCODING_PARAM
static const AVOption options[] = {
{ "loop", "Number of times to loop the output: 0 - infinite loop", OFFSET(loop),
AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 65535, ENC },
{ NULL },
};
static const AVClass webp_muxer_class = {
.class_name = "WebP muxer",
.item_name = av_default_item_name,
.version = LIBAVUTIL_VERSION_INT,
.option = options,
};
AVOutputFormat ff_webp_muxer = {
.name = "webp",
.long_name = NULL_IF_CONFIG_SMALL("WebP"),
.extensions = "webp",
.priv_data_size = sizeof(WebpContext),
.video_codec = AV_CODEC_ID_WEBP,
.write_header = webp_write_header,
.write_packet = webp_write_packet,
.write_trailer = webp_write_trailer,
.priv_class = &webp_muxer_class,
.flags = AVFMT_VARIABLE_FPS,
};