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FFmpeg/libavformat/webpenc.c
Andreas Rheinhardt b021bc4a47 avformat/webpenc: Write correct size for single images when unseekable
The earlier code writes the file and then tries to patch up
the size later. This is avoidable for the common case of
a single image because one can know the complete size
in advance and write it.

Fixes ticket #4609.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2023-12-09 06:29:42 +01:00

239 lines
7.2 KiB
C

/*
* 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 "libavcodec/bytestream.h"
#include "avformat.h"
#include "internal.h"
#include "mux.h"
typedef struct WebpContext{
AVClass *class;
int frame_count;
AVPacket *last_pkt; /* Not owned by us */
int loop;
int wrote_webp_header;
int using_webp_anim_encoder;
} WebpContext;
static int webp_init(AVFormatContext *s)
{
WebpContext *const w = s->priv_data;
AVStream *st;
w->last_pkt = ffformatcontext(s)->pkt;
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)
{
int skip = 0;
unsigned flags = 0;
if (pkt->size < 4)
return AVERROR_INVALIDDATA;
if (AV_RL32(pkt->data) == AV_RL32("RIFF"))
skip = 12;
// Safe to do this as a valid WebP bitstream is >=30 bytes.
if (pkt->size < skip + 4)
return AVERROR_INVALIDDATA;
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;
}
/**
* Returns 1 if it has written a RIFF header with a correct length field
*/
static int flush(AVFormatContext *s, int trailer, int64_t pts)
{
WebpContext *w = s->priv_data;
AVStream *st = s->streams[0];
uint8_t buf[12 /* RIFF+WEBP */ + 18 /* VP8X */ +
14 /* ANIM */ + 24 /* ANMF */], *bufp = buf;
int writing_webp_header = 0, skip = 0;
unsigned flags = 0;
int vp8x = 0;
if (!w->last_pkt->size)
return 0;
if (AV_RL32(w->last_pkt->data) == AV_RL32("RIFF"))
skip = 12;
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) {
bytestream_put_le32(&bufp, MKTAG('R', 'I', 'F', 'F'));
bytestream_put_le32(&bufp, 0); /* Size to be patched later */
bytestream_put_le32(&bufp, MKTAG('W', 'E', 'B', 'P'));
writing_webp_header = 1;
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) {
bytestream_put_le32(&bufp, MKTAG('V', 'P', '8', 'X'));
bytestream_put_le32(&bufp, 10);
bytestream_put_byte(&bufp, flags);
bytestream_put_le24(&bufp, 0);
bytestream_put_le24(&bufp, st->codecpar->width - 1);
bytestream_put_le24(&bufp, st->codecpar->height - 1);
}
if (!trailer) {
bytestream_put_le32(&bufp, MKTAG('A', 'N', 'I', 'M'));
bytestream_put_le32(&bufp, 6);
bytestream_put_le32(&bufp, 0xFFFFFFFF);
bytestream_put_le16(&bufp, w->loop);
}
}
if (w->frame_count > trailer) {
bytestream_put_le32(&bufp, MKTAG('A', 'N', 'M', 'F'));
bytestream_put_le32(&bufp, 16 + w->last_pkt->size - skip);
bytestream_put_le24(&bufp, 0);
bytestream_put_le24(&bufp, 0);
bytestream_put_le24(&bufp, st->codecpar->width - 1);
bytestream_put_le24(&bufp, st->codecpar->height - 1);
if (w->last_pkt->pts != AV_NOPTS_VALUE && pts != AV_NOPTS_VALUE) {
bytestream_put_le24(&bufp, pts - w->last_pkt->pts);
} else
bytestream_put_le24(&bufp, w->last_pkt->duration);
bytestream_put_byte(&bufp, 0);
}
if (trailer && writing_webp_header)
AV_WL32(buf + 4, bufp - (buf + 8) + w->last_pkt->size - skip);
avio_write(s->pb, buf, bufp - buf);
avio_write(s->pb, w->last_pkt->data + skip, w->last_pkt->size - skip);
av_packet_unref(w->last_pkt);
return trailer && writing_webp_header;
}
static int webp_write_packet(AVFormatContext *s, AVPacket *pkt)
{
WebpContext *w = s->priv_data;
int ret;
if (!pkt->size)
return 0;
ret = is_animated_webp_packet(pkt);
if (ret < 0)
return ret;
w->using_webp_anim_encoder |= ret;
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->loop) { // Write loop count.
if (avio_seek(s->pb, 42, SEEK_SET) == 42)
avio_wl16(s->pb, w->loop);
}
} else {
int ret;
if ((ret = flush(s, 1, AV_NOPTS_VALUE)) < 0)
return ret;
if (!ret) {
filesize = avio_tell(s->pb);
if (avio_seek(s->pb, 4, SEEK_SET) == 4) {
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,
};
const FFOutputFormat ff_webp_muxer = {
.p.name = "webp",
.p.long_name = NULL_IF_CONFIG_SMALL("WebP"),
.p.extensions = "webp",
.priv_data_size = sizeof(WebpContext),
.p.video_codec = AV_CODEC_ID_WEBP,
.init = webp_init,
.write_packet = webp_write_packet,
.write_trailer = webp_write_trailer,
.p.priv_class = &webp_muxer_class,
.p.flags = AVFMT_VARIABLE_FPS,
};