int av_probe_input_buffer(AVIOContext *pb, AVInputFormat **fmt, const char *filename, void *logctx, unsigned int offset, unsigned int max_probe_size) { AVProbeData pd = { filename ? filename : "", NULL, -offset }; unsigned char *buf = NULL; int ret = 0, probe_size; if (!max_probe_size) { max_probe_size = PROBE_BUF_MAX; } else if (max_probe_size > PROBE_BUF_MAX) { max_probe_size = PROBE_BUF_MAX; } else if (max_probe_size < PROBE_BUF_MIN) { return AVERROR(EINVAL); } if (offset >= max_probe_size) { return AVERROR(EINVAL); } for(probe_size= PROBE_BUF_MIN; probe_size<=max_probe_size && !*fmt; probe_size = FFMIN(probe_size<<1, FFMAX(max_probe_size, probe_size+1))) { int score = probe_size < max_probe_size ? AVPROBE_SCORE_RETRY : 0; int buf_offset = (probe_size == PROBE_BUF_MIN) ? 0 : probe_size>>1; void *buftmp; if (probe_size < offset) { continue; } /* read probe data */ buftmp = av_realloc(buf, probe_size + AVPROBE_PADDING_SIZE); if(!buftmp){ av_free(buf); return AVERROR(ENOMEM); } buf=buftmp; if ((ret = avio_read(pb, buf + buf_offset, probe_size - buf_offset)) < 0) { /* fail if error was not end of file, otherwise, lower score */ if (ret != AVERROR_EOF) { av_free(buf); return ret; } score = 0; ret = 0; /* error was end of file, nothing read */ } pd.buf_size += ret; pd.buf = &buf[offset]; memset(pd.buf + pd.buf_size, 0, AVPROBE_PADDING_SIZE); /* guess file format */ *fmt = av_probe_input_format2(&pd, 1, &score); if(*fmt){ if(score <= AVPROBE_SCORE_RETRY){ //this can only be true in the last iteration av_log(logctx, AV_LOG_WARNING, "Format %s detected only with low score of %d, misdetection possible!\n", (*fmt)->name, score); }else av_log(logctx, AV_LOG_DEBUG, "Format %s probed with size=%d and score=%d\n", (*fmt)->name, probe_size, score); } } if (!*fmt) { av_free(buf); return AVERROR_INVALIDDATA; } /* rewind. reuse probe buffer to avoid seeking */ ret = ffio_rewind_with_probe_data(pb, &buf, pd.buf_size); return ret; }