Add support for parsing AVIF still images. This patches supports AVIF still images that have exactly 1 item (i.e.) no alpha channel. Essentially, we will have to parse the "iloc" box and populate the mov index.
With this patch, we can decode still AVIF images like so: ffmpeg -i image.avif image.png Partially fixes trac ticket #7621 Signed-off-by: Vignesh Venkatasubramanian <vigne...@google.com> --- libavformat/isom.h | 1 + libavformat/mov.c | 137 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 138 insertions(+) diff --git a/libavformat/isom.h b/libavformat/isom.h index 5caf42b15d..02d681e3ae 100644 --- a/libavformat/isom.h +++ b/libavformat/isom.h @@ -315,6 +315,7 @@ typedef struct MOVContext { int have_read_mfra_size; uint32_t mfra_size; uint32_t max_stts_delta; + int is_still_picture_avif; } MOVContext; int ff_mp4_read_descr_len(AVIOContext *pb); diff --git a/libavformat/mov.c b/libavformat/mov.c index 6c847de164..e925690584 100644 --- a/libavformat/mov.c +++ b/libavformat/mov.c @@ -1136,6 +1136,7 @@ static int mov_read_ftyp(MOVContext *c, AVIOContext *pb, MOVAtom atom) c->isom = 1; av_log(c->fc, AV_LOG_DEBUG, "ISO: File Type Major Brand: %.4s\n",(char *)&type); av_dict_set(&c->fc->metadata, "major_brand", type, 0); + c->is_still_picture_avif = !strncmp(type, "avif", 4); minor_ver = avio_rb32(pb); /* minor version */ av_dict_set_int(&c->fc->metadata, "minor_version", minor_ver, 0); @@ -7430,6 +7431,141 @@ static int mov_read_SAND(MOVContext *c, AVIOContext *pb, MOVAtom atom) return 0; } +static int rb_size(AVIOContext *pb, uint64_t* value, int size) +{ + if (size == 0) + *value = 0; + else if (size == 1) + *value = avio_r8(pb); + else if (size == 2) + *value = avio_rb16(pb); + else if (size == 4) + *value = avio_rb32(pb); + else if (size == 8) + *value = avio_rb64(pb); + else + return -1; + return size; +} + +static int mov_read_iloc(MOVContext *c, AVIOContext *pb, MOVAtom atom) +{ + int version, offset_size, length_size, base_offset_size, index_size; + int item_count, extent_count; + uint64_t base_offset, extent_offset, extent_length; + uint8_t value; + AVStream *st; + MOVStreamContext *sc; + + if (!c->is_still_picture_avif) { + // * For non-avif, we simply ignore the iloc box. + // * For animated avif, we don't care about the iloc box as all the + // necessary information can be found in the moov box. + return 0; + } + + if (c->fc->nb_streams) { + av_log(c->fc, AV_LOG_INFO, "Duplicate iloc box found\n"); + return 0; + } + + st = avformat_new_stream(c->fc, NULL); + if (!st) + return AVERROR(ENOMEM); + st->id = c->fc->nb_streams; + sc = av_mallocz(sizeof(MOVStreamContext)); + if (!sc) + return AVERROR(ENOMEM); + + st->priv_data = sc; + st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO; + st->codecpar->codec_id = AV_CODEC_ID_AV1; + sc->ffindex = st->index; + c->trak_index = st->index; + st->avg_frame_rate.num = st->avg_frame_rate.den = 1; + st->time_base.num = st->time_base.den = 1; + st->nb_frames = 1; + sc->time_scale = 1; + sc = st->priv_data; + sc->pb = c->fc->pb; + sc->pb_is_copied = 1; + + version = avio_r8(pb); + avio_rb24(pb); // flags. + + value = avio_r8(pb); + offset_size = (value >> 4) & 0xF; + length_size = value & 0xF; + value = avio_r8(pb); + base_offset_size = (value >> 4) & 0xF; + index_size = !version ? 0 : (value & 0xF); + if (index_size) + return AVERROR_PATCHWELCOME; + item_count = (version < 2) ? avio_rb16(pb) : avio_rb32(pb); + if (item_count > 1) { + // For still AVIF images, we only support one item. Second item will + // generally be found for AVIF images with alpha channel. We don't + // support them as of now. + return AVERROR_PATCHWELCOME; + } + + // Populate the necessary fields used by mov_build_index. + sc->stsc_count = item_count; + sc->stsc_data = av_malloc_array(item_count, sizeof(*sc->stsc_data)); + if (!sc->stsc_data) + return AVERROR(ENOMEM); + sc->stsc_data[0].first = 1; + sc->stsc_data[0].count = 1; + sc->stsc_data[0].id = 1; + sc->chunk_count = item_count; + sc->chunk_offsets = + av_malloc_array(item_count, sizeof(*sc->chunk_offsets)); + if (!sc->chunk_offsets) + return AVERROR(ENOMEM); + sc->sample_count = item_count; + sc->sample_sizes = + av_malloc_array(item_count, sizeof(*sc->sample_sizes)); + if (!sc->sample_sizes) + return AVERROR(ENOMEM); + sc->stts_count = item_count; + sc->stts_data = av_malloc_array(item_count, sizeof(*sc->stts_data)); + if (!sc->stts_data) + return AVERROR(ENOMEM); + sc->stts_data[0].count = 1; + // Not used for still images. But needed by mov_build_index. + sc->stts_data[0].duration = 0; + + for (int i = 0; i < item_count; i++) { + (version < 2) ? avio_rb16(pb) : avio_rb32(pb); // item_id; + if (version > 0) + avio_rb16(pb); // construction_method. + avio_rb16(pb); // data_reference_index. + if (rb_size(pb, &base_offset, base_offset_size) < 0) + return AVERROR_INVALIDDATA; + extent_count = avio_rb16(pb); + if (extent_count > 1) { + // For still AVIF images, we only support one extent item. + return AVERROR_PATCHWELCOME; + } + for (int j = 0; j < extent_count; j++) { + if (rb_size(pb, &extent_offset, offset_size) < 0 || + rb_size(pb, &extent_length, length_size) < 0) + return AVERROR_INVALIDDATA; + sc->sample_sizes[0] = extent_length; + sc->chunk_offsets[0] = base_offset + extent_offset; + } + } + + mov_build_index(c, st); + + // For still AVIF images, the iloc box contains all the necessary + // information that would generally be provided by the moov box. So simply + // mark that we have found the moov box so that parsing can continue. + c->found_moov = 1; + + return atom.size; +} + static const MOVParseTableEntry mov_default_parse_table[] = { { MKTAG('A','C','L','R'), mov_read_aclr }, { MKTAG('A','P','R','G'), mov_read_avid }, @@ -7532,6 +7668,7 @@ static const MOVParseTableEntry mov_default_parse_table[] = { { MKTAG('k','i','n','d'), mov_read_kind }, { MKTAG('S','A','3','D'), mov_read_SA3D }, /* ambisonic audio box */ { MKTAG('S','A','N','D'), mov_read_SAND }, /* non diegetic audio box */ +{ MKTAG('i','l','o','c'), mov_read_iloc }, { 0, NULL } }; -- 2.36.0.rc0.470.gd361397f0d-goog _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".