Fix potential segfault in mlt_frame_get_waveform.

Also, reduce sample rate for better performance.

diff --git a/src/framework/mlt_frame.c b/src/framework/mlt_frame.c
index b0afaf0ebfbe60b79bcc83f5ab5c987aa3876c6b..3b644d1330babb7ea61e5ef4082c27677789c12c 100644 (file)
--- a/src/framework/mlt_frame.c
+++ b/src/framework/mlt_frame.c
@@ -692,10 +692,10 @@ unsigned char *mlt_frame_get_waveform( mlt_frame this, int w, int h )
        int16_t *pcm = NULL;
        mlt_properties properties = MLT_FRAME_PROPERTIES( this );
        mlt_audio_format format = mlt_audio_s16;
-       int frequency = 32000; // lower frequency available?
+       int frequency = 16000;
        int channels = 2;
        mlt_producer producer = mlt_frame_get_original_producer( this );
-       double fps = mlt_producer_get_fps( producer );
+       double fps = mlt_producer_get_fps( mlt_producer_cut_parent( producer ) );
        int samples = mlt_sample_calculator( fps, frequency, mlt_frame_get_position( this ) );
 
        // Get the pcm data
@@ -711,6 +711,8 @@ unsigned char *mlt_frame_get_waveform( mlt_frame this, int w, int h )
        // Render vertical lines
        int16_t *ubound = pcm + samples * channels;
        int skip = samples / w;
+       if ( !skip )
+               return NULL;
        unsigned char gray = 0xFF / skip;
        int i, j, k;