Improve audio waveform quality.

[mlt] / src / framework / mlt_frame.c

diff --git a/src/framework/mlt_frame.c b/src/framework/mlt_frame.c
index 0b9abf2076f1879e29e49442e604b21b34f5dfb5..b0afaf0ebfbe60b79bcc83f5ab5c987aa3876c6b 100644 (file)
--- a/src/framework/mlt_frame.c
+++ b/src/framework/mlt_frame.c
@@ -387,7 +387,7 @@ int mlt_frame_get_image( mlt_frame this, uint8_t **buffer, mlt_image_format *for
        {
                mlt_properties_set_int( properties, "image_count", mlt_properties_get_int( properties, "image_count" ) - 1 );
                error = get_image( this, buffer, format, width, height, writable );
-               if ( !error )
+               if ( !error && *buffer )
                {
                        mlt_properties_set_int( properties, "width", *width );
                        mlt_properties_set_int( properties, "height", *height );
@@ -407,7 +407,7 @@ int mlt_frame_get_image( mlt_frame this, uint8_t **buffer, mlt_image_format *for
                *buffer = mlt_properties_get_data( properties, "image", NULL );
                *width = mlt_properties_get_int( properties, "width" );
                *height = mlt_properties_get_int( properties, "height" );
-               if ( this->convert_image )
+               if ( this->convert_image && *buffer )
                        this->convert_image( this, buffer, format, requested_format );
        }
        else if ( producer )
@@ -694,7 +694,8 @@ unsigned char *mlt_frame_get_waveform( mlt_frame this, int w, int h )
        mlt_audio_format format = mlt_audio_s16;
        int frequency = 32000; // lower frequency available?
        int channels = 2;
-       double fps = mlt_profile_fps( NULL );
+       mlt_producer producer = mlt_frame_get_original_producer( this );
+       double fps = mlt_producer_get_fps( producer );
        int samples = mlt_sample_calculator( fps, frequency, mlt_frame_get_position( this ) );
 
        // Get the pcm data
@@ -709,33 +710,33 @@ 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 - 1;
+       int skip = samples / w;
+       unsigned char gray = 0xFF / skip;
        int i, j, k;
 
        // Iterate sample stream and along x coordinate
-       for ( i = 0; i < w && pcm < ubound; i++ )
+       for ( i = 0; pcm < ubound; i++ )
        {
                // pcm data has channels interleaved
-               for ( j = 0; j < channels; j++ )
+               for ( j = 0; j < channels; j++, pcm++ )
                {
                        // Determine sample's magnitude from 2s complement;
                        int pcm_magnitude = *pcm < 0 ? ~(*pcm) + 1 : *pcm;
                        // The height of a line is the ratio of the magnitude multiplied by
-                       // half the vertical resolution
-                       int height = ( int )( ( double )( pcm_magnitude ) / 32768 * h / 2 );
-                       // Determine the starting y coordinate - left channel above center,
-                       // right channel below - currently assumes 2 channels
-                       int displacement = ( h / 2 ) - ( 1 - j ) * height;
+                       // the vertical resolution of a single channel
+                               int height = h * pcm_magnitude / channels / 2 / 32768;
+                       // Determine the starting y coordinate - left top, right bottom
+                       int displacement = h * (j * 2 + 1) / channels / 2 - ( *pcm < 0 ? 0 : height );
                        // Position buffer pointer using y coordinate, stride, and x coordinate
-                       unsigned char *p = &bitmap[ i + displacement * w ];
+                       unsigned char *p = bitmap + i / skip + displacement * w;
 
                        // Draw vertical line
-                       for ( k = 0; k < height; k++ )
-                               p[ w * k ] = 0xFF;
-
-                       pcm++;
+                       for ( k = 0; k < height + 1; k++ )
+                               if ( *pcm < 0 )
+                                       p[ w * k ] = ( k == 0 ) ? 0xFF : p[ w * k ] + gray;
+                               else
+                                       p[ w * k ] = ( k == height ) ? 0xFF : p[ w * k ] + gray;
                }
-               pcm += skip * channels;
        }
 
        return bitmap;
@@ -812,7 +813,7 @@ int mlt_sample_calculator( float fps, int frequency, int64_t position )
  * \bug Will this break when mlt_position is converted to double?
  */
 
-inline int64_t mlt_sample_calculator_to_now( float fps, int frequency, int64_t position )
+int64_t mlt_sample_calculator_to_now( float fps, int frequency, int64_t position )
 {
        int64_t samples = 0;