[FFmpeg-devel] [PATCH]Autodetect raw flac files

[Carl Eugen Hoyos]

On Friday 10 April 2015 02:24:12 am Michael Niedermayer wrote:
> On Fri, Apr 10, 2015 at 12:13:28AM +0200, Carl Eugen Hoyos wrote:
> >  static int flac_probe(AVProbeData *p)
> >  {
> > +    if (   (AV_RB16(p->buf) & 0xFFFE) == 0xFFF8
> > +        && p->buf[2] & 0xF0        // blocksize code != 0
> > +        && p->buf[2] & 0x0F ^ 0x0F // sample rate code < 15
> > +        && (p->buf[3] & 0xF0) < FLAC_MAX_CHANNELS + FLAC_CHMODE_MID_SIDE
> > << 4 +        // channel mode < 11
> > +        && p->buf[3] & 0x06 ^ 0x06 // bits per sample code valid
> >
> > +        && p->buf[3] ^ 1)          // reserved bit not set
>
> is this missing a "& 1" ?

Definitely.

> just guessing from "bit" in the comment
>
> also maybe write it as seperate function
> so that it can be written as a series of if() instead of a long
> chain of &&, should be looking cleaner

New patch attached.

Thank you, Carl Eugen
-------------- next part --------------
diff --git a/libavformat/flacdec.c b/libavformat/flacdec.c
index 1a8dc19..4207fd2 100644
--- a/libavformat/flacdec.c
+++ b/libavformat/flacdec.c
@@ -176,8 +176,26 @@ fail:
     return ret;
 }
 
+static int raw_flac_probe(AVProbeData *p)
+{
+    if ((p->buf[2] & 0xF0) == 0)    // blocksize code invalid
+        return 0;
+    if ((p->buf[2] & 0x0F) == 0x0F) // sample rate code invalid
+        return 0;
+    if ((p->buf[3] & 0xF0) >= FLAC_MAX_CHANNELS + FLAC_CHMODE_MID_SIDE << 4)
+        // channel mode invalid
+        return 0;
+    if ((p->buf[3] & 0x06) == 0x06) // bits per sample code invalid
+        return 0;
+    if ((p->buf[3] & 0x01) == 0x01) // reserved bit set
+        return 0;
+    return AVPROBE_SCORE_EXTENSION / 4 + 1;
+}
+
 static int flac_probe(AVProbeData *p)
 {
+    if ((AV_RB16(p->buf) & 0xFFFE) == 0xFFF8)
+        return raw_flac_probe(p);
     if (p->buf_size < 4 || memcmp(p->buf, "fLaC", 4))
         return 0;
     return AVPROBE_SCORE_EXTENSION;