2018-01-06 11:07 GMT+01:00 Jörn Heusipp <osm...@problemloesungsmaschine.de>:
> When building with libopenmpt 0.3, use the libopenmpt file header
> probing functions for probing. libopenmpt probing functions are
> allocation-free and designed to be as fast as possible.
>
> For libopenmpt 0.2, or when libopenmpt 0.3 file header probing cannot
> probe successfully due to too small probe buffer, test the filename
> against the file extensions supported by the libopenmpt library that
> is actually linked, instead of relying on a hard-coded file extension
> list. File extension testing is also allocation-free and designed to
> be fast in libopenmpt. Avoiding a hard-coded file extension list is
> useful because later libopenmpt versions will likely add support for
> more module file formats.
>
> libopenmpt file header probing is tested regularly against the FATE
> suite and other diverse file collections by libopenmpt upstream in
> order to avoid false positives.
You could also test tools/probetest
> FATE passes with './configure --enable-libopenmpt' as well as with
> './configure --enable-libopenmpt --enable-libmodplug'.
>
> As expected, I did not see any measurable performance difference
> caused by libopenmpt file header probing when compared to the previous
> pure file extension based format probing (using the following
> synthetic test program (which tries to do nothing but exercise file
> probing) on the complete FATE suite).
>
> // find ../fate/ -type f | xargs --no-run-if-empty ./probetest
> #include <stdio.h>
> #include "libavformat/avformat.h"
> #define BUFSIZE 2048
> static char buf[BUFSIZE + AVPROBE_PADDING_SIZE];
> int main(int argc, const char * * argv) {
> av_log_set_level(AV_LOG_WARNING);
> av_register_all();
> for (int i = 1; i < argc; ++i) {
> AVProbeData pd;
> FILE * f;
> size_t size;
> memset(&pd, 0, sizeof(AVProbeData));
> pd.filename = argv[i];
> memset(buf, 0, sizeof(buf));
> f = fopen(pd.filename, "rb");
> size = fread(buf, 1, BUFSIZE, f);
> fclose(f);
> pd.buf_size = size;
> av_probe_input_format(&pd, 1);
> }
> return 0;
> }
>
> Signed-off-by: Jörn Heusipp <osm...@problemloesungsmaschine.de>
> ---
> libavformat/libopenmpt.c | 59
> ++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 59 insertions(+)
>
> diff --git a/libavformat/libopenmpt.c b/libavformat/libopenmpt.c
> index 5efbdc4..a663b2e 100644
> --- a/libavformat/libopenmpt.c
> +++ b/libavformat/libopenmpt.c
> @@ -218,6 +218,64 @@ static int read_seek_openmpt(AVFormatContext *s, int
> stream_idx, int64_t ts, int
> return 0;
> }
>
> +static int read_probe_openmpt(AVProbeData * p)
> +{
> + const int score_data = AVPROBE_SCORE_MIME + 1; /* 76 */
> + const int score_ext = AVPROBE_SCORE_EXTENSION; /* 50 */
> + const int score_ext_retry = AVPROBE_SCORE_RETRY; /* 25 */
> + const int score_retry = AVPROBE_SCORE_RETRY / 2; /* 12 */
> + const int score_fail = 0; /* 0 */
> +
> + const char *ext;
> + int probe_result;
> + int score = score_fail;
> +
> + if (p->filename) {
> + ext = strrchr(p->filename, '.');
> + if (ext && strlen(ext + 1) > 0) {
> + ext++; /* skip '.' */
> + if (openmpt_is_extension_supported(ext) == 1)
> + score = FFMAX(score, score_ext);
> + }
> + }
> +
> +#if OPENMPT_API_VERSION_AT_LEAST(0,3,0)
> + if (p->buf && p->buf_size > 0) {
> + probe_result = openmpt_probe_file_header_without_filesize(
> + OPENMPT_PROBE_FILE_HEADER_FLAGS_DEFAULT,
> + p->buf, p->buf_size,
> + &openmpt_logfunc, NULL, NULL, NULL, NULL, NULL);
> + if (probe_result == OPENMPT_PROBE_FILE_HEADER_RESULT_FAILURE) {
> + score = score_fail;
What's wrong with return 0;?
> + } else if (probe_result == OPENMPT_PROBE_FILE_HEADER_RESULT_SUCCESS)
> {
> + score = FFMAX(score, score_data);
What does OPENMPT_PROBE_FILE_HEADER_RESULT_SUCCESS mean?
Why not return MAX?
> + } else if (probe_result ==
> OPENMPT_PROBE_FILE_HEADER_RESULT_WANTMOREDATA) {
I believe this should return 0 but maybe you found that this is bad?
> + if (score > score_fail) {
> + /* known file extension */
> + score = FFMAX(score, score_ext_retry);
> + } else {
> + /* unknown file extension */
> + if (p->buf_size >=
> openmpt_probe_file_header_get_recommended_size()) {
> + /* We have already received the recommended amount of
> data
> + * and still cannot decide. Return a rather low score.
> + */
> + score = FFMAX(score, score_retry);
> + } else {
> + /* The file extension is unknown and we have very few
> data
> + * bytes available. libopenmpt cannot decide anything
> here,
> + * and returning any score > 0 would result in
> successfull
> + * probing of random data.
> + */
> + score = score_fail;
This patch indicates that it may be a good idea to require libopenmpt 0.3,
when was it released, which distributions do not include it?
Carl Eugen
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