avformat: move default for max_analyze_duration into utils.c

this way we can do better tha a single fixed constant value
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/avformat.h

@@ -1291,6 +1291,7 @@ typedef struct AVFormatContext {
      * Maximum duration (in AV_TIME_BASE units) of the data read
      * from input in avformat_find_stream_info().
      * Demuxing only, set by the caller before avformat_find_stream_info().
+     * Can be set to 0 to let avformat choose using a heuristic.
      */
     int max_analyze_duration;
 

libavformat/options_table.h

@@ -53,7 +53,7 @@ static const AVOption avformat_options[] = {
 {"nobuffer", "reduce the latency introduced by optional buffering", 0, AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_NOBUFFER }, 0, INT_MAX, D, "fflags"},
 {"seek2any", "allow seeking to non-keyframes on demuxer level when supported", OFFSET(seek2any), AV_OPT_TYPE_INT, {.i64 = 0 }, 0, 1, D},
 {"bitexact", "do not write random/volatile data", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_BITEXACT }, 0, 0, E, "fflags" },
-{"analyzeduration", "specify how many microseconds are analyzed to probe the input", OFFSET(max_analyze_duration), AV_OPT_TYPE_INT, {.i64 = 5*AV_TIME_BASE }, 0, INT_MAX, D},
+{"analyzeduration", "specify how many microseconds are analyzed to probe the input", OFFSET(max_analyze_duration), AV_OPT_TYPE_INT, {.i64 = 0 }, 0, INT_MAX, D},
 {"cryptokey", "decryption key", OFFSET(key), AV_OPT_TYPE_BINARY, {.dbl = 0}, 0, 0, D},
 {"indexmem", "max memory used for timestamp index (per stream)", OFFSET(max_index_size), AV_OPT_TYPE_INT, {.i64 = 1<<20 }, 0, INT_MAX, D},
 {"rtbufsize", "max memory used for buffering real-time frames", OFFSET(max_picture_buffer), AV_OPT_TYPE_INT, {.i64 = 3041280 }, 0, INT_MAX, D}, /* defaults to 1s of 15fps 352x288 YUYV422 video */

libavformat/utils.c

@@ -3289,6 +3289,11 @@ int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
         }
         if (st->codec_info_nb_frames>1) {
             int64_t t = 0;
+            int max_analyze_duration = ic->max_analyze_duration;
+
+            if (!max_analyze_duration)
+                max_analyze_duration = 5*AV_TIME_BASE;
+
             if (st->time_base.den > 0)
                 t = av_rescale_q(st->info->codec_info_duration, st->time_base, AV_TIME_BASE_Q);
             if (st->avg_frame_rate.num > 0)
@@ -3300,9 +3305,9 @@ int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
                 && st->info->fps_last_dts  != AV_NOPTS_VALUE)
                 t = FFMAX(t, av_rescale_q(st->info->fps_last_dts - st->info->fps_first_dts, st->time_base, AV_TIME_BASE_Q));
 
-            if (t >= ic->max_analyze_duration) {
+            if (t >= max_analyze_duration) {
                 av_log(ic, AV_LOG_VERBOSE, "max_analyze_duration %d reached at %"PRId64" microseconds\n",
-                       ic->max_analyze_duration,
+                       max_analyze_duration,
                        t);
                 break;
             }