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MP3File: tweak buffer handling

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After adding the ability to change files in an existing MP3File object,
it became apparent that at the beginning of a track some part of an
existing buffer was playing first.

I noticed that in get_buffer, the just-populated buffer wasn't being
returned, but the other one was.  But still after fixing this, I heard
wrong audio at the beginning of a track, so I took the heavy duty approach
and zeroed the buffers out.  That means there's a remaining bug to chase,
which is merely hidden by the memset()s.
This commit is contained in:
Jeff Epler 2019-12-24 09:43:15 -06:00
parent 5aa3e3eabb
commit 97bb46c047
1 changed files with 10 additions and 3 deletions
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13
shared-module/audiomp3/MP3File.c
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@ -215,6 +215,13 @@ void common_hal_audiomp3_mp3file_set_file(audiomp3_mp3file_obj_t* self, pyb_file
self->other_channel = -1;
mp3file_update_inbuf(self);
mp3file_find_sync_word(self);
// It **SHOULD** not be necessary to do this; the buffer should be filled
// with fresh content before it is returned by get_buffer(). The fact that
// this is necessary to avoid a glitch at the start of playback of a second
// track using the same decoder object means there's still a bug in
// get_buffer() that I didn't understand.
memset(self->buffers[0], 0, MAX_BUFFER_LEN);
memset(self->buffers[1], 0, MAX_BUFFER_LEN);
MP3FrameInfo fi;
if(!mp3file_get_next_frame_info(self, &fi)) {
mp_raise_msg(&mp_type_RuntimeError,
@ -290,7 +297,6 @@ audioio_get_buffer_result_t audiomp3_mp3file_get_buffer(audiomp3_mp3file_obj_t*
channel = 0;
}
*bufptr = (uint8_t*)(self->buffers[self->buffer_index] + channel);
*buffer_length = self->frame_buffer_size;
if (channel == self->other_channel) {
@ -299,11 +305,12 @@ audioio_get_buffer_result_t audiomp3_mp3file_get_buffer(audiomp3_mp3file_obj_t*
return GET_BUFFER_MORE_DATA;
}
self->other_channel = 1-channel;
self->other_buffer_index = self->buffer_index;
self->buffer_index = !self->buffer_index;
self->other_channel = 1-channel;
self->other_buffer_index = self->buffer_index;
int16_t *buffer = (int16_t *)(void *)self->buffers[self->buffer_index];
*bufptr = (uint8_t*)buffer;
mp3file_skip_id3v2(self);
if (!mp3file_find_sync_word(self)) {