21/1/20 11:14 pm, Carl Eugen Hoyos пишет:
>
> Am Di., 21. Jan. 2020 um 11:09 Uhr schrieb Zane van Iperen
> <z...@zanevaniperen.com>:
>
>> +static int argo_asf_probe(const AVProbeData *p)
>> +{
>> + int score;
>> + ArgoASFFileHeader hdr;
>> +
>> + av_assert0(AVPROBE_PADDING_SIZE >= ASF_FILE_HEADER_SIZE);
>> +
>> + argo_asf_parse_file_header(&hdr, p->buf);
>> +
>> + if (hdr.magic != ASF_TAG)
>> + return 0;
>
>> + /* If this is huge, then it's very likely not an ASF file. */
>> + if (hdr.chunk_offset > INT_MAX)
>> + return 1;
>
> Am I correct that this tests only one bit?
> This makes sense for many probe functions that can easily
> return false positives based on weak heuristics, probe
> functions typically return high scores for matching first 32
> bits though.
>
I can just get rid of that check completely if it's easier.
>> + score = 0;
>> + if (argo_asf_is_known_version(&hdr))
>> + score += (AVPROBE_SCORE_MAX / 2) + 1;
>
> Unusual code style.
>
>> + /* Have only ever seen these with 1 chunk. */
>> + if (hdr.num_chunks == 1)
>> + score += 10;
>
> Returns 0 for argo files with unknown version and more than
> one chunk and 10 for for unknown version and one chunk.
>
> Should be ~25 in both cases, feel free to return a higher
> score if all tests pass, I just wanted to simplify the probe
> function as testing 32 bit is what is usually done.
>
Returning 0 on a unknown version is a bug, I want it to hit the
avpriv_request_sample() below.
Would something like this (untested) be better?
> if (hdr.chunk_offset & 0xFF000000U)
> return 1;
>
> score = (AVPROBE_SCORE_MAX / 2) + 1;
>
> if (!argo_asf_is_known_version(&hdr))
> score -= 25;
>
> /* Have only ever seen these with 1 chunk. */
> if (hdr.num_chunks > 1)
> score -= 25;
>
> return score;
That way if it fails one check it'll be 26, or 1 if it fails both.
> Carl Eugen
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Zane
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