[Ffmpeg-devel] [PATCH] MP3 decoding from RTP stream. Getting "invalid new backstep"

[Michael Niedermayer]

Hi
On Mon, Nov 06, 2006 at 05:44:07PM +0100, Martin wrote:
> Hi
> 
> Michael Niedermayer wrote:
> > Hi
> > 
> > On Mon, Nov 06, 2006 at 03:19:10PM +0100, Martin wrote:
> > [...]
> > 
> >>>>>>       assert(i <= buf_size - HEADER_SIZE && i>= 0);
> >>>>>>       memcpy(s->last_buf + s->last_buf_size, s->gb.buffer + buf_size - HEADER_SIZE - i, i);
> >>>>>>@@ -2503,6 +2508,19 @@ static int mp_decode_frame(MPADecodeCont
> >>>>>>       }
> >>>>>>   }
> >>>>>>#endif
> >>>>>>+
> >>>>>>+    // zero samples if frame is distorted by overread or backstep
> >>>>>>+    if (discard_frame) {
> >>>>>>+        for(i=0;i<nb_frames;i++) {
> >>>>>>+            for(ch=0;ch<s->nb_channels;ch++) {
> >>>>>>+                int j;
> >>>>>>+                for(j=0;j<SBLIMIT;j++) {
> >>>>>>+                    s->sb_samples[ch][i][j] = 0;
> >>>>>>+                }
> >>>>>>+            }
> >>>>>>+        }
> >>>>>>+    }
> >>>>>
> >>>>>
> >>>>>memset(0);
> >>>>>
> >>>>>[...]
> >>>>
> >>>>Is the rest of the patch ok?
> >>>
> >>>
> >>>i think so, but thats just from memory ...
> >>>
> >>>[...]
> >>
> >>The new patch which sets buffers to 0 if 'backstep'occurs which prior
> >>resulted in distorted sound is attached.
> > 
> > [...]
> > 
> > 
> >>+    // zero samples if frame is distorted by overread or backstep
> >>+    if (discard_frame) {
> >>+        for(i=0;i<nb_frames;i++) {
> >>+            for(ch=0;ch<s->nb_channels;ch++) {
> >>+                int j;
> >>+                for(j=0;j<SBLIMIT;j++) {
> >>+                    s->sb_samples[ch][i][j] = 0;
> >>+                }
> >>+            }
> >>+        }
> >>+    }
> > 
> > 
> > the whole above should be replaced by a if (discard_frame) \n memset(..., 0, ...)
> > as already said
> > 
> > [...]
> 
> Ok, I didn't see that. Obviously its much better that way... :)
> Attached the updated patch. Hope everything is finally ok now... ;)

looks ok

whoever applies this should test it with a damaged mp3 though

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
Today you'd get arrested for mere telling someone where the library is