[vlc-devel] [PATCH 2/2] audio_filter: add RNNoise denoiser filter

[Steve Lhomme]

Also

>> +
>> +#ifdef HAVE_CONFIG_H
>> +# include "config.h"
>> +#endif
>> +
>> +#include <vlc_common.h>
>> +#include <vlc_aout.h>
>> +#include <vlc_filter.h>
>> +#include <vlc_plugin.h>
>> +
>> +#include <rnnoise.h>
>> +
>> +typedef struct
>> +{
>> +    DenoiseState **p_sts;
>> +    bool b_first;
>> +} filter_sys_t;
>> +
>> +static void
>> +Flush(filter_t *p_filter)
>> +{
>> +    filter_sys_t *p_sys = p_filter->p_sys;
>> +
>> +    if (p_sys->p_sts) {
>> +        int i_channels = p_filter->fmt_in.audio.i_channels;
>> +        for (int i = 0; i < i_channels; i++) {
>> +            rnnoise_destroy( p_sys->p_sts[i] );
>> +        }
>> +        free(p_sys->p_sts);
>> +        p_sys->p_sts = NULL;
>> +        p_sys->b_first = true;
>> +    }
>> +}
>> +
>> +static DenoiseState **init_denoise_state(unsigned i_channels)
>> +{
>> +    DenoiseState **p_sts = malloc(i_channels * sizeof(DenoiseState *));
>> +    if (unlikely(!p_sts))
>> +        return NULL;
>> +
>> +    for (unsigned i = 0; i < i_channels; i++)
>> +    {
>> +        p_sts[i] = rnnoise_create(NULL);
>> +        if (unlikely(!p_sts[i]))
>> +        {
>> +            for (unsigned j = 0; j < i; j++)
>> +                rnnoise_destroy( p_sts[j] );
>> +
>> +            return NULL;
>> +        }
>> +    }
>> +
>> +    return p_sts;
>> +}
>> +
>> +
>> +#define FRAME_SIZE 480

Is this an arbitrary value or is it fixed in the library ? In which case 
we should use their define.

>> +
>> +static block_t *Process(filter_t *p_filter, block_t *p_block)
>> +{
>> +    filter_sys_t *p_sys = p_filter->p_sys;
>> +    float *p_buffer = (float *)p_block->p_buffer;
>> +    const int i_channels = p_filter->fmt_in.audio.i_channels;
>> +
>> +    float *tmp = malloc(FRAME_SIZE * i_channels * sizeof(*tmp));

Since the size is fixed and used for all blocks, locally, you should put 
it in filter_sys_t once.

>> +    if (unlikely(!tmp))
>> +    {
>> +        return p_block;
>> +    }
>> +
>> +    if (unlikely(p_sys->p_sts == NULL))
>> +    {
>> +        /* Can happen after a flush */
>> +        p_sys->p_sts = init_denoise_state(i_channels);
>> +        if (p_sys->p_sts == NULL)
>> +            return p_block;
>> +    }
>> +
>> +    for (int i_nb_samples = p_block->i_nb_samples; i_nb_samples > 0; 
>> i_nb_samples -= FRAME_SIZE)
>> +    {
>> +        /* handle case where we have fewer than FRAME_SIZE samples 
>> left to process */
>> +        const unsigned frame_size = __MIN(FRAME_SIZE, i_nb_samples);
>> +
>> +        /* rnnoise processes blocks of 480 samples, and expects input 
>> to be in the 32768 scale. */
>> +        for (unsigned i = 0; i < frame_size; i++) {
>> +            for (int j = 0; j < i_channels; j++) {
>> +                tmp[i + j * frame_size] = p_buffer[i * i_channels + 
>> j] * 32768.f;
>> +            }
>> +        }
>> +
>> +        for (int i = 0; i < i_channels; i++) {
>> +            rnnoise_process_frame(p_sys->p_sts[i], tmp + i * 
>> frame_size , tmp + i * frame_size);
>> +        }
>> +
>> +        /* Skip writing first frame to output (as per the examples) I 
>> guess to prime rnnoise? */
>> +        if(!p_sys->b_first)
>> +        {
>> +            for (unsigned i = 0; i < frame_size; i++) {
>> +                for (int j = 0; j < i_channels; j++) {
>> +                    p_buffer[i * i_channels + j] = tmp[i + j * 
>> frame_size] / 32768.f;
>> +                }
>> +            }
>> +        }
>> +        else
>> +        {
>> +            p_sys->b_first = false;
>> +        }
>> +        p_buffer += frame_size * i_channels;
>> +    }
>> +
>> +    free(tmp);
>> +    return p_block;
>> +}
>> +
>> +static void Close( filter_t *obj )
>> +{
>> +    filter_t *p_filter = (filter_t *)obj;
>> +    Flush( p_filter );
>> +    free( p_filter->p_sys );
>> +}
>> +
>> +static int Open (vlc_object_t *obj)
>> +{
>> +    filter_t *p_filter = (filter_t *)obj;
>> +
>> +    filter_sys_t *p_sys = p_filter->p_sys = 
>> malloc(sizeof(filter_sys_t));
> 
> You can allocate the p_sys with vlc_obj_malloc() so you don't have to 
> free it manually in Close. (and then it only calls Flush, surprise!)
> 
>> +    if(unlikely(!p_sys))
>> +        return VLC_ENOMEM;
>> +
>> +    p_sys->b_first = true;
>> +
>> +    int i_channels = p_filter->fmt_in.audio.i_channels;
>> +    p_sys->p_sts = init_denoise_state(i_channels);
>> +    if (unlikely(!p_sys->p_sts))
>> +    {
>> +        free( p_sys );
> 
> Which becomes vlc_obj_free().
> 
>> +        return VLC_ENOMEM;
>> +    }
>> +
>> +    p_filter->fmt_in.audio.i_format = VLC_CODEC_FL32;
>> +    aout_FormatPrepare(&p_filter->fmt_in.audio);
>> +    p_filter->fmt_out.audio = p_filter->fmt_in.audio;
>> +
>> +    static const struct vlc_filter_operations filter_ops =
>> +    {
>> +        .filter_audio = Process, .flush = Flush, .close = Close,
>> +    };
>> +    p_filter->ops = &filter_ops;
>> +
>> +    return VLC_SUCCESS;
>> +}
>> +
>> +vlc_module_begin ()
>> +    set_shortname (N_("RNNoise"))
>> +    set_description (N_("RNNoise filter"))
>> +    set_category (CAT_AUDIO)
>> +    set_subcategory (SUBCAT_AUDIO_AFILTER)
>> +    set_capability ("audio filter", 0)
>> +    set_callback( Open )
>> +vlc_module_end ()
>> diff --git a/po/POTFILES.in b/po/POTFILES.in
>> index 2395e6fc0a..e924ec061c 100644
>> --- a/po/POTFILES.in
>> +++ b/po/POTFILES.in
>> @@ -247,6 +247,7 @@ modules/audio_filter/resampler/soxr.c
>>   modules/audio_filter/resampler/speex.c
>>   modules/audio_filter/resampler/src.c
>>   modules/audio_filter/resampler/ugly.c
>> +modules/audio_filter/rnnoise.c
>>   modules/audio_filter/scaletempo.c
>>   modules/audio_filter/spatializer/spatializer.cpp
>>   modules/audio_filter/stereo_widen.c
>> -- 
>> 2.25.1
>>
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