[FFmpeg-devel] [PATCH 2/2] avformat/apngdec: add APNG demuxer.
Benoit Fouet
benoit.fouet at free.fr
Thu Nov 20 15:07:18 CET 2014
---
libavformat/Makefile | 1 +
libavformat/allformats.c | 1 +
libavformat/apngdec.c | 409 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 411 insertions(+)
create mode 100644 libavformat/apngdec.c
diff --git a/libavformat/Makefile b/libavformat/Makefile
index 38730c5..c1b5ace 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -76,6 +76,7 @@ OBJS-$(CONFIG_AMR_MUXER) += amr.o
OBJS-$(CONFIG_ANM_DEMUXER) += anm.o
OBJS-$(CONFIG_APC_DEMUXER) += apc.o
OBJS-$(CONFIG_APE_DEMUXER) += ape.o apetag.o img2.o
+OBJS-$(CONFIG_APNG_DEMUXER) += apngdec.o
OBJS-$(CONFIG_AQTITLE_DEMUXER) += aqtitledec.o subtitles.o
OBJS-$(CONFIG_ASF_DEMUXER) += asfdec.o asf.o asfcrypt.o \
avlanguage.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 3f60d7d..81aab56 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -74,6 +74,7 @@ void av_register_all(void)
REGISTER_DEMUXER (ANM, anm);
REGISTER_DEMUXER (APC, apc);
REGISTER_DEMUXER (APE, ape);
+ REGISTER_DEMUXER (APNG, apng);
REGISTER_DEMUXER (AQTITLE, aqtitle);
REGISTER_MUXDEMUX(ASF, asf);
REGISTER_MUXDEMUX(ASS, ass);
diff --git a/libavformat/apngdec.c b/libavformat/apngdec.c
new file mode 100644
index 0000000..54fbd29
--- /dev/null
+++ b/libavformat/apngdec.c
@@ -0,0 +1,409 @@
+/*
+ * APNG demuxer
+ * Copyright (c) 2014 Benoit Fouet
+ *
+ * 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
+ * APNG demuxer.
+ * @see https://wiki.mozilla.org/APNG_Specification
+ * @see http://www.w3.org/TR/PNG
+ *
+ * Not supported (yet):
+ * - streams with chunks other than fcTL / fdAT / IEND after the first fcTL
+ * - streams with multiple fdAT chunks after an fcTL one
+ */
+
+#include "avformat.h"
+#include "avio_internal.h"
+#include "internal.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/intreadwrite.h"
+#include "libavutil/opt.h"
+#include "libavcodec/png.h"
+#include "libavcodec/bytestream.h"
+
+#define DEFAULT_APNG_FPS 15
+
+typedef struct APNGDemuxContext {
+ const AVClass *class;
+
+ int max_fps;
+ int default_fps;
+
+ int is_key_frame;
+
+ /*
+ * loop options
+ */
+ int ignore_loop;
+ uint32_t num_frames;
+ uint32_t num_play;
+ uint32_t cur_loop;
+} APNGDemuxContext;
+
+/*
+ * To be a valid APNG file, we mandate, in this order:
+ * PNGSIG
+ * IHDR
+ * ...
+ * acTL
+ * ...
+ * IDAT
+ */
+static int apng_probe(AVProbeData *p)
+{
+ GetByteContext gb;
+ int state = 0;
+ uint32_t len, tag;
+
+ bytestream2_init(&gb, p->buf, p->buf_size);
+
+ if (bytestream2_get_be64(&gb) != PNGSIG)
+ return 0;
+
+ for (;;) {
+ len = bytestream2_get_be32(&gb);
+ if (len > 0x7fffffff)
+ return 0;
+
+ tag = bytestream2_get_le32(&gb);
+ /* we don't check IDAT size, as this is the last tag
+ * we check, and it may be larger than the probe buffer */
+ if (tag != MKTAG('I', 'D', 'A', 'T') &&
+ len > bytestream2_get_bytes_left(&gb))
+ return 0;
+
+ switch (tag) {
+ case MKTAG('I', 'H', 'D', 'R'):
+ if (len != 13)
+ return 0;
+ if (av_image_check_size(bytestream2_get_be32(&gb), bytestream2_get_be32(&gb), 0, NULL))
+ return 0;
+ bytestream2_skip(&gb, 9);
+ state++;
+ break;
+ case MKTAG('a', 'c', 'T', 'L'):
+ if (state != 1 ||
+ len != 8 ||
+ bytestream2_get_be32(&gb) == 0) /* 0 is not a valid value for number of frames */
+ return 0;
+ bytestream2_skip(&gb, 8);
+ state++;
+ break;
+ case MKTAG('I', 'D', 'A', 'T'):
+ if (state != 2)
+ return 0;
+ goto end;
+ default:
+ /* skip other tags */
+ bytestream2_skip(&gb, len + 4);
+ break;
+ }
+ }
+
+end:
+ return AVPROBE_SCORE_MAX;
+}
+
+static int append_extradata(AVCodecContext *s, AVIOContext *pb, int len)
+{
+ int previous_size = s->extradata_size;
+ int new_size, ret;
+ uint8_t *new_extradata;
+
+ if (previous_size > INT_MAX - len)
+ return AVERROR_INVALIDDATA;
+
+ new_size = previous_size + len;
+ new_extradata = av_realloc(s->extradata, new_size + FF_INPUT_BUFFER_PADDING_SIZE);
+ if (!new_extradata)
+ return AVERROR(ENOMEM);
+ s->extradata = new_extradata;
+ s->extradata_size = new_size;
+
+ if ((ret = avio_read(pb, s->extradata + previous_size, len)) < 0)
+ return ret;
+
+ return previous_size;
+}
+
+static int apng_read_header(AVFormatContext *s)
+{
+ APNGDemuxContext *ctx = s->priv_data;
+ AVIOContext *pb = s->pb;
+ uint32_t len, tag;
+ AVStream *st;
+ int ret = AVERROR_INVALIDDATA, acTL_found = 0;
+
+ /* verify PNGSIG */
+ if (avio_rb64(pb) != PNGSIG)
+ return ret;
+
+ /* parse IHDR (must be first chunk) */
+ len = avio_rb32(pb);
+ tag = avio_rl32(pb);
+ if (len != 13 || tag != MKTAG('I', 'H', 'D', 'R'))
+ return ret;
+
+ st = avformat_new_stream(s, NULL);
+ if (!st)
+ return AVERROR(ENOMEM);
+
+ st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
+ st->codec->codec_id = AV_CODEC_ID_APNG;
+ st->codec->width = avio_rb32(pb);
+ st->codec->height = avio_rb32(pb);
+ if ((ret = av_image_check_size(st->codec->width, st->codec->height, 0, s)) < 0)
+ return ret;
+
+ /* extradata will contain every chunk up to the first fcTL (excluded) */
+ st->codec->extradata = av_malloc(len + 12 + FF_INPUT_BUFFER_PADDING_SIZE);
+ if (!st->codec->extradata)
+ return AVERROR(ENOMEM);
+ st->codec->extradata_size = len + 12;
+ AV_WB32(st->codec->extradata, len);
+ AV_WL32(st->codec->extradata+4, tag);
+ AV_WB32(st->codec->extradata+8, st->codec->width);
+ AV_WB32(st->codec->extradata+12, st->codec->height);
+ if ((ret = avio_read(pb, st->codec->extradata+16, 9)) < 0)
+ goto fail;
+
+ while (!avio_feof(pb)) {
+ if (acTL_found && ctx->num_play != 1) {
+ int64_t size = avio_size(pb);
+ int64_t offset = avio_tell(pb);
+ if (size < 0) {
+ ret = size;
+ goto fail;
+ } else if (offset < 0) {
+ ret = offset;
+ goto fail;
+ } else if ((ret = ffio_ensure_seekback(pb, size - offset)) < 0) {
+ av_log(s, AV_LOG_WARNING, "Could not ensure seekback, will not loop\n");
+ ctx->num_play = 1;
+ }
+ }
+ if ((ctx->num_play == 1 || !acTL_found) &&
+ ((ret = ffio_ensure_seekback(pb, 4 /* len */ + 4 /* tag */)) < 0))
+ goto fail;
+
+ len = avio_rb32(pb);
+ if (len > 0x7fffffff) {
+ ret = AVERROR_INVALIDDATA;
+ goto fail;
+ }
+
+ tag = avio_rl32(pb);
+ switch (tag) {
+ case MKTAG('a', 'c', 'T', 'L'):
+ if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
+ (ret = append_extradata(st->codec, pb, len + 12)) < 0)
+ goto fail;
+ acTL_found = 1;
+ ctx->num_frames = AV_RB32(st->codec->extradata + ret + 8);
+ ctx->num_play = AV_RB32(st->codec->extradata + ret + 12);
+ av_log(s, AV_LOG_DEBUG, "num_frames: %"PRIu32", num_play: %"PRIu32"\n",
+ ctx->num_frames, ctx->num_play);
+ break;
+ case MKTAG('f', 'c', 'T', 'L'):
+ if (!acTL_found) {
+ ret = AVERROR_INVALIDDATA;
+ goto fail;
+ }
+ if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0)
+ goto fail;
+ return 0;
+ default:
+ if ((ret = avio_seek(pb, -8, SEEK_CUR)) < 0 ||
+ (ret = append_extradata(st->codec, pb, len + 12)) < 0)
+ goto fail;
+ }
+ }
+
+fail:
+ if (st->codec->extradata_size) {
+ av_freep(&st->codec->extradata);
+ st->codec->extradata_size = 0;
+ }
+ return ret;
+}
+
+static int decode_fctl_chunk(AVFormatContext *s, APNGDemuxContext *ctx, AVPacket *pkt)
+{
+ uint32_t sequence_number, width, height, x_offset, y_offset;
+ uint16_t delay_num, delay_den;
+ uint8_t dispose_op, blend_op;
+
+ sequence_number = avio_rb32(s->pb);
+ width = avio_rb32(s->pb);
+ height = avio_rb32(s->pb);
+ x_offset = avio_rb32(s->pb);
+ y_offset = avio_rb32(s->pb);
+ delay_num = avio_rb16(s->pb);
+ delay_den = avio_rb16(s->pb);
+ dispose_op = avio_r8(s->pb);
+ blend_op = avio_r8(s->pb);
+ avio_skip(s->pb, 4); /* crc */
+
+ /* default is hundredths of seconds */
+ if (!delay_den)
+ delay_den = 100;
+ if (!delay_num || delay_den / delay_num > ctx->max_fps) {
+ delay_num = 1;
+ delay_den = ctx->default_fps;
+ }
+ s->streams[0]->r_frame_rate.num = delay_den;
+ s->streams[0]->r_frame_rate.den = delay_num;
+ pkt->duration = 1;
+
+ av_log(s, AV_LOG_DEBUG, "%s: "
+ "sequence_number: %"PRId32", "
+ "width: %"PRIu32", "
+ "height: %"PRIu32", "
+ "x_offset: %"PRIu32", "
+ "y_offset: %"PRIu32", "
+ "delay_num: %"PRIu16", "
+ "delay_den: %"PRIu16", "
+ "dispose_op: %d, "
+ "blend_op: %d\n",
+ __func__,
+ sequence_number,
+ width,
+ height,
+ x_offset,
+ y_offset,
+ delay_num,
+ delay_den,
+ dispose_op,
+ blend_op);
+
+ if (width != s->streams[0]->codec->width ||
+ height != s->streams[0]->codec->height ||
+ x_offset != 0 ||
+ y_offset != 0) {
+ if (sequence_number == 0)
+ return AVERROR_INVALIDDATA;
+ ctx->is_key_frame = 0;
+ } else {
+ ctx->is_key_frame = 1;
+ }
+
+ return 0;
+}
+
+static int apng_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+ APNGDemuxContext *ctx = s->priv_data;
+ int ret;
+ int64_t size;
+ AVIOContext *pb = s->pb;
+ uint32_t len, tag;
+
+ /*
+ * fcTL chunk length, in bytes:
+ * 4 (length)
+ * 4 (tag)
+ * 26 (actual chunk)
+ * 4 (crc) bytes
+ * and needed next:
+ * 4 (length)
+ * 4 (tag (must be fdAT or IDAT))
+ *
+ * TODO: support multiple fdAT following an fcTL
+ */
+ /* if num_play is not 1, then the seekback is already guaranteed */
+ if (ctx->num_play == 1 && (ret = ffio_ensure_seekback(pb, 46)) < 0)
+ return ret;
+
+ len = avio_rb32(pb);
+ tag = avio_rl32(pb);
+ switch (tag) {
+ case MKTAG('f', 'c', 'T', 'L'):
+ if (len != 26)
+ return AVERROR_INVALIDDATA;
+
+ if ((ret = decode_fctl_chunk(s, ctx, pkt)) < 0)
+ return ret;
+
+ /* fcTL must precede fdAT or IDAT */
+ len = avio_rb32(pb);
+ tag = avio_rl32(pb);
+ if (len > 0x7fffffff ||
+ tag != MKTAG('f', 'd', 'A', 'T') &&
+ tag != MKTAG('I', 'D', 'A', 'T'))
+ return AVERROR_INVALIDDATA;
+
+ if ((ret = avio_seek(pb, -46, SEEK_CUR)) < 0)
+ return ret;
+
+ size = 38 /* fcTL */ + 8 /* len, tag */ + len + 4 /* crc */;
+ if (size > INT_MAX)
+ return AVERROR(EINVAL);
+
+ if ((ret = av_get_packet(pb, pkt, size)) < 0)
+ return ret;
+ if (ctx->is_key_frame)
+ pkt->flags |= AV_PKT_FLAG_KEY;
+ return ret;
+ case MKTAG('I', 'E', 'N', 'D'):
+ ctx->cur_loop++;
+ if (ctx->ignore_loop || ctx->num_play >= 1 && ctx->cur_loop == ctx->num_play) {
+ avio_seek(pb, -8, SEEK_CUR);
+ return AVERROR_EOF;
+ }
+ if ((ret = avio_seek(pb, s->streams[0]->codec->extradata_size + 8, SEEK_SET)) < 0)
+ return ret;
+ return 0;
+ default:
+ avpriv_request_sample(s, "In-stream tag=%#08X len=%"PRId64"", tag, avio_tell(pb));
+ }
+
+ /* Handle the unsupported yet cases */
+ return AVERROR_PATCHWELCOME;
+}
+
+static const AVOption options[] = {
+ { "ignore_loop", "ignore loop setting" , offsetof(APNGDemuxContext, ignore_loop),
+ AV_OPT_TYPE_INT, { .i64 = 1 } , 0, 1 , AV_OPT_FLAG_DECODING_PARAM },
+ { "max_fps" , "maximum framerate (0 is no limit)" , offsetof(APNGDemuxContext, max_fps),
+ AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
+ { "default_fps", "default framerate (0 is as fast as possible)", offsetof(APNGDemuxContext, default_fps),
+ AV_OPT_TYPE_INT, { .i64 = DEFAULT_APNG_FPS }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
+ { NULL },
+};
+
+static const AVClass demuxer_class = {
+ .class_name = "APNG demuxer",
+ .item_name = av_default_item_name,
+ .option = options,
+ .version = LIBAVUTIL_VERSION_INT,
+ .category = AV_CLASS_CATEGORY_DEMUXER,
+};
+
+AVInputFormat ff_apng_demuxer = {
+ .name = "apng",
+ .long_name = NULL_IF_CONFIG_SMALL("Animated Portable Network Graphics"),
+ .priv_data_size = sizeof(APNGDemuxContext),
+ .read_probe = apng_probe,
+ .read_header = apng_read_header,
+ .read_packet = apng_read_packet,
+ .flags = AVFMT_GENERIC_INDEX,
+ .priv_class = &demuxer_class,
+};
--
2.2.0.rc2.23.gca0107e
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