avformat: Use the mime type information in input probe

It should provide a quicker guess for elementary streams provided
by http.

libavformat/avformat.h

@@ -391,9 +391,13 @@ typedef struct AVProbeData {
     const char *filename;
     unsigned char *buf; /**< Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero. */
     int buf_size;       /**< Size of buf except extra allocated bytes */
+#ifdef FF_API_PROBE_MIME
+    uint8_t *mime_type; /**< mime_type, when known. */
+#endif
 } AVProbeData;
 
 #define AVPROBE_SCORE_EXTENSION  50 ///< score for file extension
+#define AVPROBE_SCORE_MIME       75 ///< score for file mime type
 #define AVPROBE_SCORE_MAX       100 ///< maximum score
 
 #define AVPROBE_PADDING_SIZE 32             ///< extra allocated bytes at the end of the probe buffer
@@ -535,6 +539,13 @@ typedef struct AVInputFormat {
 
     const AVClass *priv_class; ///< AVClass for the private context
 
+    /**
+     * Comma-separated list of mime types.
+     * It is used check for matching mime types while probing.
+     * @see av_probe_input_format2
+     */
+    const char *mime_type;
+
     /*****************************************************************
      * No fields below this line are part of the public API. They
      * may not be used outside of libavformat and can be changed and

libavformat/format.c

@@ -20,6 +20,7 @@
  */
 
 #include "libavutil/avstring.h"
+#include "libavutil/opt.h"
 
 #include "avio_internal.h"
 #include "avformat.h"
@@ -194,6 +195,10 @@ AVInputFormat *av_probe_input_format2(AVProbeData *pd, int is_opened,
             if (av_match_ext(lpd.filename, fmt1->extensions))
                 score = AVPROBE_SCORE_EXTENSION;
         }
+#ifdef FF_API_PROBE_MIME
+        if (av_match_name(lpd.mime_type, fmt1->mime_type))
+            score = FFMAX(score, AVPROBE_SCORE_EXTENSION);
+#endif
         if (score > *score_max) {
             *score_max = score;
             fmt        = fmt1;
@@ -251,7 +256,10 @@ int av_probe_input_buffer(AVIOContext *pb, AVInputFormat **fmt,
         return AVERROR(EINVAL);
     avio_skip(pb, offset);
     max_probe_size -= offset;
-
+#ifdef FF_API_PROBE_MIME
+    if (pb->av_class)
+        av_opt_get(pb, "mime_type", AV_OPT_SEARCH_CHILDREN, &pd.mime_type);
+#endif
     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))) {
@@ -259,14 +267,13 @@ int av_probe_input_buffer(AVIOContext *pb, AVInputFormat **fmt,
 
         /* Read probe data. */
         if ((ret = av_reallocp(&buf, probe_size + AVPROBE_PADDING_SIZE)) < 0)
-            return ret;
+            goto fail;
         if ((ret = avio_read(pb, buf + pd.buf_size,
                              probe_size - pd.buf_size)) < 0) {
             /* Fail if error was not end of file, otherwise, lower score. */
-            if (ret != AVERROR_EOF) {
-                av_free(buf);
-                return ret;
-            }
+            if (ret != AVERROR_EOF)
+                goto fail;
+
             score = 0;
             ret   = 0;          /* error was end of file, nothing read */
         }
@@ -289,14 +296,17 @@ int av_probe_input_buffer(AVIOContext *pb, AVInputFormat **fmt,
         }
     }
 
-    if (!*fmt) {
-        av_free(buf);
-        return AVERROR_INVALIDDATA;
-    }
+    if (!*fmt)
+        ret = AVERROR_INVALIDDATA;
 
+fail:
     /* Rewind. Reuse probe buffer to avoid seeking. */
-    if ((ret = ffio_rewind_with_probe_data(pb, buf, pd.buf_size)) < 0)
+    if (ret < 0 ||
+        (ret = ffio_rewind_with_probe_data(pb, buf, pd.buf_size)) < 0) {
         av_free(buf);
-
+    }
+#ifdef FF_API_PROBE_MIME
+    av_free(pd.mime_type);
+#endif
     return ret;
 }

libavformat/version.h

@@ -61,4 +61,8 @@
 #define FF_API_LAVF_CODEC_TB            (LIBAVFORMAT_VERSION_MAJOR < 57)
 #endif
 
+#ifndef FF_API_PROBE_MIME
+#define FF_API_PROBE_MIME               (LIBAVFORMAT_VERSION_MAJOR > 55)
+#endif
+
 #endif /* AVFORMAT_VERSION_H */