lavf: replace FFFormatContext.prefer_codec_framerate with FF_INFMT_FLAG

There is no reason for this to be a dynamic property, as the only
demuxer using this sets it unconditionally.

libavformat/demux.c

@@ -2946,7 +2946,8 @@ int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
                         best_fps   = std_fps.num;
                     }
 
-                    if (si->prefer_codec_framerate && codec_frame_rate.num > 0 && codec_frame_rate.den > 0) {
+                    if ((ffifmt(ic->iformat)->flags_internal & FF_INFMT_FLAG_PREFER_CODEC_FRAMERATE) &&
+                        codec_frame_rate.num > 0 && codec_frame_rate.den > 0) {
                         error       = fabs(av_q2d(codec_frame_rate) /
                                            av_q2d(std_fps) - 1);
                         if (error < best_error) {

libavformat/demux.h

@@ -34,6 +34,11 @@ struct AVDeviceInfoList;
  */
 #define FF_INFMT_FLAG_INIT_CLEANUP                             (1 << 0)
 
+/*
+ * Prefer the codec framerate for avg_frame_rate computation.
+ */
+#define FF_INFMT_FLAG_PREFER_CODEC_FRAMERATE                   (1 << 1)
+
 typedef struct FFInputFormat {
     /**
      * The public AVInputFormat. See avformat.h for it.

libavformat/internal.h

@@ -120,11 +120,6 @@ typedef struct FFFormatContext {
      * ID3v2 tag useful for MP3 demuxing
      */
     AVDictionary *id3v2_meta;
-
-    /*
-     * Prefer the codec framerate for avg_frame_rate computation.
-     */
-    int prefer_codec_framerate;
 } FFFormatContext;
 
 static av_always_inline FFFormatContext *ffformatcontext(AVFormatContext *s)

libavformat/mpegts.c

@@ -3113,8 +3113,6 @@ static int mpegts_read_header(AVFormatContext *s)
     int64_t pos, probesize = s->probesize;
     int64_t seekback = FFMAX(s->probesize, (int64_t)ts->resync_size + PROBE_PACKET_MAX_BUF);
 
-    ffformatcontext(s)->prefer_codec_framerate = 1;
-
     if (ffio_ensure_seekback(pb, seekback) < 0)
         av_log(s, AV_LOG_WARNING, "Failed to allocate buffers for seekback\n");
 
@@ -3446,6 +3444,7 @@ const FFInputFormat ff_mpegts_demuxer = {
     .read_packet    = mpegts_read_packet,
     .read_close     = mpegts_read_close,
     .read_timestamp = mpegts_get_dts,
+    .flags_internal  = FF_INFMT_FLAG_PREFER_CODEC_FRAMERATE,
 };
 
 const FFInputFormat ff_mpegtsraw_demuxer = {
@@ -3458,4 +3457,5 @@ const FFInputFormat ff_mpegtsraw_demuxer = {
     .read_packet    = mpegts_raw_read_packet,
     .read_close     = mpegts_read_close,
     .read_timestamp = mpegts_get_dts,
+    .flags_internal  = FF_INFMT_FLAG_PREFER_CODEC_FRAMERATE,
 };