- // preprocess audio (volume)
- if (audio_volume != 256) {
- int decoded_data_size = decoded_frame->nb_samples * avctx->channels * bps;
- void *samples = decoded_frame->data[0];
- switch (avctx->sample_fmt) {
- case AV_SAMPLE_FMT_U8:
- {
- uint8_t *volp = samples;
- for (i = 0; i < (decoded_data_size / sizeof(*volp)); i++) {
- int v = (((*volp - 128) * audio_volume + 128) >> 8) + 128;
- *volp++ = av_clip_uint8(v);
- }
- break;
- }
- case AV_SAMPLE_FMT_S16:
- {
- int16_t *volp = samples;
- for (i = 0; i < (decoded_data_size / sizeof(*volp)); i++) {
- int v = ((*volp) * audio_volume + 128) >> 8;
- *volp++ = av_clip_int16(v);
- }
- break;
- }
- case AV_SAMPLE_FMT_S32:
- {
- int32_t *volp = samples;
- for (i = 0; i < (decoded_data_size / sizeof(*volp)); i++) {
- int64_t v = (((int64_t)*volp * audio_volume + 128) >> 8);
- *volp++ = av_clipl_int32(v);
- }
- break;
- }
- case AV_SAMPLE_FMT_FLT:
- {
- float *volp = samples;
- float scale = audio_volume / 256.f;
- for (i = 0; i < (decoded_data_size / sizeof(*volp)); i++) {
- *volp++ *= scale;
- }
- break;
- }
- case AV_SAMPLE_FMT_DBL:
- {
- double *volp = samples;
- double scale = audio_volume / 256.;
- for (i = 0; i < (decoded_data_size / sizeof(*volp)); i++) {
- *volp++ *= scale;
- }
- break;
- }
- default:
- av_log(NULL, AV_LOG_FATAL,
- "Audio volume adjustment on sample format %s is not supported.\n",
- av_get_sample_fmt_name(ist->st->codec->sample_fmt));
- exit_program(1);
- }
- }
-