Fix crashes when cards deliver empty audio frames (especially 0-channel).

diff --git a/mixer.cpp b/mixer.cpp
index a1c038d5329abc21ad0e9a5015e0575f7658b959..06fc5f043f60f87c66ae112d865a09042be8a564 100644 (file)
--- a/mixer.cpp
+++ b/mixer.cpp
@@ -351,7 +351,7 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
 
        int64_t frame_length = int64_t(TIMEBASE * video_format.frame_rate_den) / video_format.frame_rate_nom;
 
-       size_t num_samples = (audio_frame.len >= audio_offset) ? (audio_frame.len - audio_offset) / audio_format.num_channels / (audio_format.bits_per_sample / 8) : 0;
+       size_t num_samples = (audio_frame.len > audio_offset) ? (audio_frame.len - audio_offset) / audio_format.num_channels / (audio_format.bits_per_sample / 8) : 0;
        if (num_samples > OUTPUT_FREQUENCY / 10) {
                printf("Card %d: Dropping frame with implausible audio length (len=%d, offset=%d) [timecode=0x%04x video_len=%d video_offset=%d video_format=%x)\n",
                        card_index, int(audio_frame.len), int(audio_offset),
@@ -375,6 +375,9 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
        vector<float> audio;
        audio.resize(num_samples * 2);
        switch (audio_format.bits_per_sample) {
+       case 0:
+               assert(num_samples == 0);
+               break;
        case 24:
                convert_fixed24_to_fp32(&audio[0], 2, audio_frame.data + audio_offset, audio_format.num_channels, num_samples);
                break;