avformat/img2dec: Use avformat probing interface to identify format if it has not been otherwise identified

This is used only for distinguishing .pix formats for now.
Which is the only case that has image2 demuxers currently

Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/img2dec.c

@@ -298,6 +298,8 @@ int ff_img_read_header(AVFormatContext *s1)
         st->codec->codec_id   = ff_guess_image2_codec(s->path);
         if (st->codec->codec_id == AV_CODEC_ID_LJPEG)
             st->codec->codec_id = AV_CODEC_ID_MJPEG;
+        if (st->codec->codec_id == AV_CODEC_ID_ALIAS_PIX) // we cannot distingiush this from BRENDER_PIX
+            st->codec->codec_id = AV_CODEC_ID_NONE;
     }
     if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO &&
         pix_fmt != AV_PIX_FMT_NONE)
@@ -349,6 +351,26 @@ int ff_img_read_packet(AVFormatContext *s1, AVPacket *pkt)
             filename[strlen(filename) - 1] = 'U' + i;
         }
 
+        if (codec->codec_id == AV_CODEC_ID_NONE) {
+            AVProbeData pd;
+            AVInputFormat *ifmt;
+            uint8_t header[20 + AVPROBE_PADDING_SIZE];
+            int ret;
+            int score = 0;
+
+            ret = avio_read(f[0], header, 20);
+            if (ret < 0)
+                return ret;
+            avio_skip(f[0], -ret);
+            pd.buf = header;
+            pd.buf_size = ret;
+            pd.filename = filename;
+
+            ifmt = av_probe_input_format3(&pd, 1, &score);
+            if (ifmt && ifmt->read_packet == ff_img_read_packet && ifmt->raw_codec_id)
+                codec->codec_id = ifmt->raw_codec_id;
+        }
+
         if (codec->codec_id == AV_CODEC_ID_RAWVIDEO && !codec->width)
             infer_size(&codec->width, &codec->height, size[0]);
     } else {

libavformat/version.h

@@ -30,8 +30,8 @@
 #include "libavutil/version.h"
 
 #define LIBAVFORMAT_VERSION_MAJOR 55
-#define LIBAVFORMAT_VERSION_MINOR 35
-#define LIBAVFORMAT_VERSION_MICRO 102
+#define LIBAVFORMAT_VERSION_MINOR 36
+#define LIBAVFORMAT_VERSION_MICRO 100
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \