如何识别mpegts文件?我从这里复制了下面的代码，它在很多文件上工作得很好，但他也将这个文件识别为mpegts视频。下面是有问题的文件的开头。
这是我使用的代码:
#define MPEGTS_MIN_BUF_SIZE 1024 * 4
static __forceinline const uint16_t av_bswap16(uint16_t x)
{
x = (x >> 8) | (x << 8);
return x;
}
#define AV_RB16(x) av_bswap16(x)
#define bswap16(x) ((x)>>8 | ((x)&255)<<8) // https://stackoverflow.com/a/648215/7206675
#define FFMAX(a,b) ((a) > (b) ? (a) : (b))
#define FFMAX3(a,b,c) FFMAX(FFMAX(a,b),c)
#define FFMIN(a,b) ((a) > (b) ? (b) : (a))
#define FFMIN3(a,b,c) FFMIN(FFMIN(a,b),c)
static int analyze2(const uint8_t* buf, int size, int packet_size,
int probe)
{
int stat[TS_MAX_PACKET_SIZE];
int stat_all = 0;
int i;
int best_score = 0;
memset(stat, 0, packet_size * sizeof(*stat));
for (i = 0; i < size - 3; i++)
{
if (buf[i] == 0x47)
{
int pid = AV_RB16(buf + 1) & 0x1FFF;
int asc = buf[i + 3] & 0x30;
if (!probe || pid == 0x1FFF || asc)
{
int x = i % packet_size;
stat[x]++;
stat_all++;
if (stat[x] > best_score)
{
best_score = stat[x];
}
}
}
}
return best_score - FFMAX(stat_all - 10 * best_score, 0) / 10;
}
/**
* This structure contains the data a format has to probe a file.
*/
typedef struct AVProbeData {
const char* filename;
unsigned char* buf; /**< Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero. */
int buf_size; /**< Size of buf except extra allocated bytes */
const char* mime_type; /**< mime_type, when known. */
} AVProbeData;
#define AVPROBE_SCORE_MAX 100 ///< maximum score
static int mpegts_probe(const AVProbeData* p)
{
const int size = p->buf_size;
int maxscore = 0;
int sumscore = 0;
int i;
int check_count = size / TS_FEC_PACKET_SIZE;
#define CHECK_COUNT 10
#define CHECK_BLOCK 100
if (!check_count)
return 0;
for (i = 0; i < check_count; i += CHECK_BLOCK) {
int left = FFMIN(check_count - i, CHECK_BLOCK);
int score = analyze2(p->buf + TS_PACKET_SIZE * i, TS_PACKET_SIZE * left, TS_PACKET_SIZE, 1);
int dvhs_score = analyze2(p->buf + TS_DVHS_PACKET_SIZE * i, TS_DVHS_PACKET_SIZE * left, TS_DVHS_PACKET_SIZE, 1);
int fec_score = analyze2(p->buf + TS_FEC_PACKET_SIZE * i, TS_FEC_PACKET_SIZE * left, TS_FEC_PACKET_SIZE, 1);
score = FFMAX3(score, dvhs_score, fec_score);
sumscore += score;
maxscore = FFMAX(maxscore, score);
}
sumscore = sumscore * CHECK_COUNT / check_count;
maxscore = maxscore * CHECK_COUNT / CHECK_BLOCK;
//ff_dlog(0, "TS score: %d %dn", sumscore, maxscore);
if (check_count > CHECK_COUNT && sumscore > 6) {
return AVPROBE_SCORE_MAX + sumscore - CHECK_COUNT;
}
else if (check_count >= CHECK_COUNT && sumscore > 6) {
return AVPROBE_SCORE_MAX / 2 + sumscore - CHECK_COUNT;
}
else if (check_count >= CHECK_COUNT && maxscore > 6) {
return AVPROBE_SCORE_MAX / 2 + sumscore - CHECK_COUNT;
}
else if (sumscore > 6) {
return 2;
}
else {
return 0;
}
}
int main()
{
BOOL IsMpegtsVideo = FALSE;
char buf[MPEGTS_MIN_BUF_SIZE];
ReadMyTestFile(buf);
AVProbeData p;
p.buf = buf;
p.buf_size = MPEGTS_MIN_BUF_SIZE;
int score = mpegts_probe(&p);
IsMpegtsVideo = score > 0;
return 0;
}
这是被错误识别为视频的文件的开头:
#ifdef TARGET_ABI32
/*
* Linux N32 syscalls are in the range from 6000 to 6999.
*/
#define TARGET_NR_Linux 6000
#define TARGET_NR_read (TARGET_NR_Linux + 0)
#define TARGET_NR_write (TARGET_NR_Linux + 1)
#define TARGET_NR_open (TARGET_NR_Linux + 2)
#define TARGET_NR_close (TARGET_NR_Linux + 3)
#define TARGET_NR_stat (TARGET_NR_Linux + 4)
#define TARGET_NR_fstat (TARGET_NR_Linux + 5)
#define TARGET_NR_lstat (TARGET_NR_Linux + 6)
#define TARGET_NR_poll (TARGET_NR_Linux + 7)
#define TARGET_NR_lseek (TARGET_NR_Linux + 8)
#define TARGET_NR_mmap (TARGET_NR_Linux + 9)
#define TARGET_NR_mprotect (TARGET_NR_Linux + 10)
#define TARGET_NR_munmap (TARGET_NR_Linux + 11)
#define TARGET_NR_brk (TARGET_NR_Linux + 12)
#define TARGET_NR_rt_sigaction (TARGET_NR_Linux + 13)
#define TARGET_NR_rt_sigprocmask (TARGET_NR_Linux + 14)
#define TARGET_NR_ioctl (TARGET_NR_Linux + 15)
#define TARGET_NR_pread64 (TARGET_NR_Linux + 16)
#define TARGET_NR_pwrite64 (TARGET_NR_Linux + 17)
#define TARGET_NR_readv (TARGET_NR_Linux + 18)
#define TARGET_NR_writev (TARGET_NR_Linux + 19)
#define TARGET_NR_access (TARGET_NR_Linux + 20)
#define TARGET_NR_pipe (TARGET_NR_Linux + 21)
#define TARGET_NR__newselect (TARGET_NR_Linux + 22)
#define TARGET_NR_sched_yield (TARGET_NR_Linux + 23)
#define TARGET_NR_mremap (TARGET_NR_Linux + 24)
#define TARGET_NR_msync (TARGET_NR_Linux + 25)
#define TARGET_NR_mincore (TARGET_NR_Linux + 26)
#define TARGET_NR_madvise (TARGET_NR_Linux + 27)
#define TARGET_NR_shmget (TARGET_NR_Linux + 28)
#define TARGET_NR_shmat (TARGET_NR_Linux + 29)
#define TARGET_NR_shmctl (TARGET_NR_Linux + 30)
#define TARGET_NR_dup (TARGET_NR_Linux + 31)
#define TARGET_NR_dup2 (TARGET_NR_Linux + 32)
我如何改进我的代码，使它不识别上述文件为视频，另一方面继续识别为实际上是视频的视频文件?
需要检查Pid字段-Packet identifier flag, used to associate one packet with a set。它可以有很多有效值，但必须先有PatPid,SdtPid这样的值。如果这些值没有出现在第一个数据包中，那么它可能不是视频。
public enum PidType
{
PatPid = 0x0,
CatPid = 0x1,
TsDescPid = 0x2,
NitPid = 0x10,
SdtPid = 0x11,
EitPid = 0x12,
NullPid = 0x1FFF
}