El 23/10/18 a las 12:59, Matthieu Regnauld escribió:
Thank you for your help.
That said, I'm new to FFMpeg, and I still struggle.
Could you tell me what I have to fix in my code to have a clear sound
and also, if possible, how to resample it (from 44100 Hz to 48000 Hz,
for example)?
Here is my code:
https://gist.github.com/mregnauld/2538d98308ad57eb75cfcd36aab5099a
Thank you.
First, you need to set swrContext to NULL at the beginning, like:
AVFrame *frame = NULL; SwrContext *swrContext = NULL;
Then, here you should set the output frequency:
int out_sample_rate = 48000;
swr_alloc_set_opts(swrContext, AV_CH_LAYOUT_STEREO, AV_SAMPLE_FMT_FLT,
out_sample_rate,
codecContext->channel_layout,
codecContext->sample_fmt, codecContext->sample_rate, 0,
NULL);
Then, you should not need to memcpy anything as that's what swr_convert
should do for you. However, you might want to set your buffer bigger
than two channels as avcodec_receive_frame might return multiple frames
of sound. By doing that, you won't have to worry about overrunning the
buffer. Also, you might want to use extended_data, for formats that
have more than 4 channels.
// Somewhere else
localBuffer = av_malloc( sizeof(float) * out_sample_rate * nb_samples +
padding);
//
swr_convert(swrContext, (uint8_t**)&localBuffer, frame->nb_samples,
(const uint8_t **) frame->extended_data, frame->nb_samples);
--
Gonzalo Garramuño
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