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avformat/flvdec: implement support for parsing ModEx data

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This commit is contained in:
Timo Rothenpieler 2025-01-15 01:19:57 +01:00
parent 4c96d6bf75
commit ced9fddec0
2 changed files with 73 additions and 0 deletions
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5
libavformat/flv.h
View file

@ -130,6 +130,7 @@ enum {
PacketTypeMetadata = 4,
PacketTypeMPEG2TSSequenceStart = 5,
PacketTypeMultitrack = 6,
PacketTypeModEx = 7,
};
enum {
@ -139,6 +140,10 @@ enum {
AudioPacketTypeMultitrack = 5,
};
enum {
PacketModExTypeTimestampOffsetNano = 0,
};
enum {
AudioChannelOrderUnspecified = 0,
AudioChannelOrderNative = 1,

68
libavformat/flvdec.c
View file

@ -1279,6 +1279,62 @@ static int flv_update_video_color_info(AVFormatContext *s, AVStream *st)
return 0;
}
static int flv_parse_mod_ex_data(AVFormatContext *s, int *pkt_type, int *size, int64_t *dts)
{
int ex_type, ret;
uint8_t *ex_data;
int ex_size = (uint8_t)avio_r8(s->pb) + 1;
*size -= 1;
if (ex_size == 256) {
ex_size = (uint16_t)avio_rb16(s->pb) + 1;
*size -= 2;
}
if (ex_size >= *size) {
av_log(s, AV_LOG_WARNING, "ModEx size larger than remaining data!\n");
return AVERROR(EINVAL);
}
ex_data = av_malloc(ex_size);
if (!ex_data)
return AVERROR(ENOMEM);
ret = avio_read(s->pb, ex_data, ex_size);
if (ret < 0) {
av_free(ex_data);
return ret;
}
*size -= ex_size;
ex_type = (uint8_t)avio_r8(s->pb);
*size -= 1;
*pkt_type = ex_type & 0x0f;
ex_type &= 0xf0;
if (ex_type == PacketModExTypeTimestampOffsetNano) {
uint32_t nano_offset;
if (ex_size != 3) {
av_log(s, AV_LOG_WARNING, "Invalid ModEx size for Type TimestampOffsetNano!\n");
nano_offset = 0;
} else {
nano_offset = (ex_data[0] << 16) | (ex_data[1] << 8) | ex_data[2];
}
// this is not likely to ever add anything, but right now timestamps are with ms precision
*dts += nano_offset / 1000000;
} else {
av_log(s, AV_LOG_INFO, "Unknown ModEx type: %d", ex_type);
}
av_free(ex_data);
return 0;
}
static int flv_read_packet(AVFormatContext *s, AVPacket *pkt)
{
FLVContext *flv = s->priv_data;
@ -1347,6 +1403,12 @@ retry:
enhanced_flv = 1;
pkt_type = flags & ~FLV_AUDIO_CODECID_MASK;
while (pkt_type == PacketTypeModEx) {
ret = flv_parse_mod_ex_data(s, &pkt_type, &size, &dts);
if (ret < 0)
goto leave;
}
if (pkt_type == AudioPacketTypeMultitrack) {
uint8_t types = avio_r8(s->pb);
multitrack_type = types & 0xF0;
@ -1376,6 +1438,12 @@ retry:
pkt_type = enhanced_flv ? codec_id : 0;
size--;
while (pkt_type == PacketTypeModEx) {
ret = flv_parse_mod_ex_data(s, &pkt_type, &size, &dts);
if (ret < 0)
goto leave;
}
if (pkt_type == PacketTypeMultitrack) {
uint8_t types = avio_r8(s->pb);
multitrack_type = types & 0xF0;