[FFmpeg-devel] [PATCH V2 2/3] avormat/av1dec: add low-overhead bitstream format
Xu Guangxin
guangxin.xu at intel.com
Mon Aug 10 12:34:31 EEST 2020
It's defined in Section 5.2, used by netflix.
see http://download.opencontent.netflix.com/?prefix=AV1/Chimera/
---
configure | 1 +
libavformat/allformats.c | 1 +
libavformat/av1dec.c | 266 +++++++++++++++++++++++++++++++++++----
3 files changed, 245 insertions(+), 23 deletions(-)
diff --git a/configure b/configure
index 8de1afcb99..d4a1fea9ce 100755
--- a/configure
+++ b/configure
@@ -3331,6 +3331,7 @@ mxf_d10_muxer_select="mxf_muxer"
mxf_opatom_muxer_select="mxf_muxer"
nut_muxer_select="riffenc"
nuv_demuxer_select="riffdec"
+obu_demuxer_select="av1_frame_merge_bsf av1_parser"
oga_muxer_select="ogg_muxer"
ogg_demuxer_select="dirac_parse"
ogv_muxer_select="ogg_muxer"
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index b7e59ae170..0aa9dd7198 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -293,6 +293,7 @@ extern AVOutputFormat ff_null_muxer;
extern AVInputFormat ff_nut_demuxer;
extern AVOutputFormat ff_nut_muxer;
extern AVInputFormat ff_nuv_demuxer;
+extern AVInputFormat ff_obu_demuxer;
extern AVOutputFormat ff_oga_muxer;
extern AVInputFormat ff_ogg_demuxer;
extern AVOutputFormat ff_ogg_muxer;
diff --git a/libavformat/av1dec.c b/libavformat/av1dec.c
index 1be2fac1c1..14efb8f1d4 100644
--- a/libavformat/av1dec.c
+++ b/libavformat/av1dec.c
@@ -70,6 +70,24 @@ static int read_obu(const uint8_t *buf, int size, int64_t *obu_size, int *type)
return 0;
}
+//return < 0 if we need more data
+static int get_score(int type, int *seq)
+{
+ switch (type) {
+ case AV1_OBU_SEQUENCE_HEADER:
+ *seq = 1;
+ return -1;
+ case AV1_OBU_FRAME:
+ case AV1_OBU_FRAME_HEADER:
+ return *seq ? AVPROBE_SCORE_EXTENSION + 1 : 0;
+ case AV1_OBU_METADATA:
+ return -1;
+ default:
+ break;
+ }
+ return 0;
+}
+
static int annexb_probe(const AVProbeData *p)
{
AVIOContext pb;
@@ -123,19 +141,9 @@ static int annexb_probe(const AVProbeData *p)
return 0;
cnt += obu_unit_size;
- switch (type) {
- case AV1_OBU_SEQUENCE_HEADER:
- seq = 1;
- break;
- case AV1_OBU_FRAME:
- case AV1_OBU_FRAME_HEADER:
- return seq ? AVPROBE_SCORE_EXTENSION + 1 : 0;
- case AV1_OBU_TILE_GROUP:
- case AV1_OBU_TEMPORAL_DELIMITER:
- return 0;
- default:
- break;
- }
+ ret = get_score(type, &seq);
+ if (ret >= 0)
+ return ret;
temporal_unit_size -= obu_unit_size + ret;
frame_unit_size -= obu_unit_size + ret;
@@ -144,15 +152,14 @@ static int annexb_probe(const AVProbeData *p)
return 0;
}
-static int annexb_read_header(AVFormatContext *s)
+static int read_header(AVFormatContext *s, AVRational framerate, AVBSFContext **bsf, void *logctx)
{
- AnnexBContext *c = s->priv_data;
const AVBitStreamFilter *filter = av_bsf_get_by_name("av1_frame_merge");
AVStream *st;
int ret;
if (!filter) {
- av_log(c, AV_LOG_ERROR, "av1_frame_merge bitstream filter "
+ av_log(logctx, AV_LOG_ERROR, "av1_frame_merge bitstream filter "
"not found. This is a bug, please report it.\n");
return AVERROR_BUG;
}
@@ -165,25 +172,32 @@ static int annexb_read_header(AVFormatContext *s)
st->codecpar->codec_id = AV_CODEC_ID_AV1;
st->need_parsing = AVSTREAM_PARSE_HEADERS;
- st->internal->avctx->framerate = c->framerate;
+ st->internal->avctx->framerate = framerate;
// taken from rawvideo demuxers
avpriv_set_pts_info(st, 64, 1, 1200000);
- ret = av_bsf_alloc(filter, &c->bsf);
+ ret = av_bsf_alloc(filter, bsf);
if (ret < 0)
return ret;
- ret = avcodec_parameters_copy(c->bsf->par_in, st->codecpar);
+ ret = avcodec_parameters_copy((*bsf)->par_in, st->codecpar);
if (ret < 0) {
- av_bsf_free(&c->bsf);
+ av_bsf_free(bsf);
return ret;
}
- ret = av_bsf_init(c->bsf);
+ ret = av_bsf_init(*bsf);
if (ret < 0)
- av_bsf_free(&c->bsf);
+ av_bsf_free(bsf);
return ret;
+
+}
+
+static int annexb_read_header(AVFormatContext *s)
+{
+ AnnexBContext *c = s->priv_data;
+ return read_header(s, c->framerate, &c->bsf, c);
}
static int annexb_read_packet(AVFormatContext *s, AVPacket *pkt)
@@ -251,12 +265,198 @@ static int annexb_read_close(AVFormatContext *s)
return 0;
}
-#define OFFSET(x) offsetof(AnnexBContext, x)
+typedef struct ObuContext {
+ const AVClass *class;
+ AVBSFContext *bsf;
+ AVRational framerate;
+ uint8_t prefetched[MAX_OBU_HEADER_SIZE];
+ //prefetched len
+ int len;
+} ObuContext;
+
+//For low overhead obu, we can't foresee the obu size before we parsed the header.
+//So, we can't use parse_obu_header here, since it will check size <= buf_size
+//see c27c7b49dc for more details
+static int read_obu_with_size(const uint8_t *buf, int buf_size, int64_t *obu_size, int *type)
+{
+ GetBitContext gb;
+ int ret, extension_flag, start_pos;
+ int64_t size;
+
+ ret = init_get_bits8(&gb, buf, FFMIN(buf_size, MAX_OBU_HEADER_SIZE));
+ if (ret < 0)
+ return ret;
+
+ if (get_bits1(&gb) != 0) // obu_forbidden_bit
+ return AVERROR_INVALIDDATA;
+
+ *type = get_bits(&gb, 4);
+ extension_flag = get_bits1(&gb);
+ if (!get_bits1(&gb)) // has_size_flag
+ return AVERROR_INVALIDDATA;
+ skip_bits1(&gb); // obu_reserved_1bit
+
+ if (extension_flag) {
+ get_bits(&gb, 3); // temporal_id
+ get_bits(&gb, 2); // spatial_id
+ skip_bits(&gb, 3); // extension_header_reserved_3bits
+ }
+
+ *obu_size = leb128(&gb);
+ if (*obu_size > INT_MAX)
+ return AVERROR_INVALIDDATA;
+
+ if (get_bits_left(&gb) < 0)
+ return AVERROR_INVALIDDATA;
+
+ start_pos = get_bits_count(&gb) / 8;
+
+ size = *obu_size + start_pos;
+ if (size > INT_MAX)
+ return AVERROR_INVALIDDATA;
+ return size;
+}
+
+static int obu_probe(const AVProbeData *p)
+{
+ int64_t obu_size;
+ int seq = 0;
+ int ret, type, cnt;
+
+ // Check that the first OBU is a Temporal Delimiter.
+ cnt = read_obu_with_size(p->buf, p->buf_size, &obu_size, &type);
+ if (cnt < 0 || type != AV1_OBU_TEMPORAL_DELIMITER || obu_size != 0)
+ return 0;
+
+ while (1) {
+ ret = read_obu_with_size(p->buf + cnt, p->buf_size - cnt, &obu_size, &type);
+ if (ret < 0 || obu_size <= 0)
+ return 0;
+ cnt += ret;
+
+ ret = get_score(type, &seq);
+ if (ret >= 0)
+ return ret;
+ }
+ return 0;
+}
+
+static int obu_read_header(AVFormatContext *s)
+{
+ ObuContext *c = s->priv_data;
+ return read_header(s, c->framerate, &c->bsf, c);
+}
+
+static int obu_prefetch(AVFormatContext *s)
+{
+ ObuContext *c = s->priv_data;
+ int ret;
+ int size = MAX_OBU_HEADER_SIZE - c->len;
+ if (size > 0 && !avio_feof(s->pb)) {
+ ret = avio_read(s->pb, &c->prefetched[c->len], size);
+ if (ret < 0)
+ return ret;
+ c->len += ret;
+ }
+ return c->len;
+}
+
+static int obu_read_data(AVFormatContext *s, AVPacket *pkt, int size)
+{
+ int left;
+ ObuContext *c = s->priv_data;
+ int ret = av_new_packet(pkt, size);
+ if (ret < 0) {
+ av_log(c, AV_LOG_ERROR, "Failed to allocate packet for obu\n");
+ return ret;
+ }
+ if (size <= c->len) {
+ memcpy(pkt->data, c->prefetched, size);
+
+ left = c->len - size;
+ memmove(c->prefetched, c->prefetched + size, left);
+ c->len = left;
+ } else {
+ memcpy(pkt->data, c->prefetched, c->len);
+ left = size - c->len;
+ ret = avio_read(s->pb, pkt->data + c->len, left);
+ if (ret != left) {
+ av_log(c, AV_LOG_ERROR, "Failed to read %d frome file\n", left);
+ return ret;
+ }
+ c->len = 0;
+ }
+ return 0;
+}
+
+static int obu_get_packet(AVFormatContext *s, AVPacket *pkt)
+{
+ int64_t obu_size;
+ int ret, type;
+ ObuContext *c = s->priv_data;
+ ret = obu_prefetch(s);
+ if (ret < 0)
+ return ret;
+ if (ret) {
+ ret = read_obu_with_size(c->prefetched, c->len, &obu_size, &type);
+ if (ret < 0) {
+ av_log(c, AV_LOG_ERROR, "Failed to read obu\n");
+ return ret;
+ }
+ ret = obu_read_data(s, pkt, ret);
+ }
+ return ret;
+}
+
+static int obu_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+ ObuContext *c = s->priv_data;
+ int ret;
+
+ while (1) {
+ ret = obu_get_packet(s, pkt);
+ if (ret < 0)
+ return ret;
+ ret = av_bsf_send_packet(c->bsf, pkt);
+ if (ret < 0) {
+ av_log(s, AV_LOG_ERROR, "Failed to send packet to "
+ "av1_frame_merge filter\n");
+ return ret;
+ }
+ ret = av_bsf_receive_packet(c->bsf, pkt);
+ if (ret < 0 && ret != AVERROR(EAGAIN) && ret != AVERROR_EOF)
+ av_log(s, AV_LOG_ERROR, "av1_frame_merge filter failed to "
+ "send output packet\n");
+ if (ret != AVERROR(EAGAIN))
+ break;
+ }
+
+ return ret;
+}
+
+static int obu_read_close(AVFormatContext *s)
+{
+ ObuContext *c = s->priv_data;
+
+ av_bsf_free(&c->bsf);
+ return 0;
+}
+
#define DEC AV_OPT_FLAG_DECODING_PARAM
+
+#define OFFSET(x) offsetof(AnnexBContext, x)
static const AVOption annexb_options[] = {
{ "framerate", "", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "25"}, 0, INT_MAX, DEC},
{ NULL },
};
+#undef OFFSET
+
+#define OFFSET(x) offsetof(ObuContext, x)
+static const AVOption obu_options[] = {
+ { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "25"}, 0, INT_MAX, DEC},
+ { NULL },
+};
+#undef OFFSET
static const AVClass annexb_demuxer_class = {
.class_name = "AV1 Annex B demuxer",
@@ -277,3 +477,23 @@ AVInputFormat ff_av1_demuxer = {
.flags = AVFMT_GENERIC_INDEX,
.priv_class = &annexb_demuxer_class,
};
+
+static const AVClass obu_demuxer_class = {
+ .class_name = "AV1 low overhead OBU demuxer",
+ .item_name = av_default_item_name,
+ .option = obu_options,
+ .version = LIBAVUTIL_VERSION_INT,
+};
+
+AVInputFormat ff_obu_demuxer = {
+ .name = "obu",
+ .long_name = NULL_IF_CONFIG_SMALL("AV1 low overhead OBU"),
+ .priv_data_size = sizeof(ObuContext),
+ .read_probe = obu_probe,
+ .read_header = obu_read_header,
+ .read_packet = obu_read_packet,
+ .read_close = obu_read_close,
+ .extensions = "obu",
+ .flags = AVFMT_GENERIC_INDEX,
+ .priv_class = &obu_demuxer_class,
+};
--
2.17.1
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