[FFmpeg-devel] [PATCH] lavfi: add aecho filter

[Paul B Mahol]

On 7/9/13, Timothy Gu <timothygu99 at gmail.com> wrote:
> On Jul 9, 2013 7:53 AM, "Paul B Mahol" <onemda at gmail.com> wrote:
>> + at item delay1..7
>
> delay1 through delay7. Same below
>
>> +Set time interval in miliseconds between original signal and reflection.
>> +
>> + at item decay1..7
>> +Loudness of reflected signal.
>> +
>> + at end table
>> +
>
> [...]
>
>> diff --git a/libavfilter/af_aecho.c b/libavfilter/af_aecho.c
>> new file mode 100644
>> index 0000000..9d4010d
>> --- /dev/null
>> +++ b/libavfilter/af_aecho.c
>> @@ -0,0 +1,297 @@
>
> [...]
>
>> +#define MAX_ECHOS 7
>
> MAX_ECHOES

Isn't both echoes and echos valid?

>
> This is also not documented directly (although users can infer from the
> options numbering).
>
>> +
>> +typedef struct AudioEchoContext {
>> +    const AVClass *class;
>> +    float in_gain, out_gain;
>> +    float delay[MAX_ECHOS], decay[MAX_ECHOS];
>> +    int nb_echos;
>> +    int delay_index;
>> +    uint8_t **delayptrs;
>> +    int max_samples, fade_out;
>> +    int samples[MAX_ECHOS];
>> +    int64_t next_pts;
>> +
>> +    void (*echo_samples)(struct AudioEchoContext *ctx, uint8_t
> **delayptrs,
>> +                         uint8_t * const *src, uint8_t **dst,
>> +                         int nb_samples, int channels);
>> +} AudioEchoContext;
>> +
>> +#define OFFSET(x) offsetof(AudioEchoContext, x)
>> +#define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
>> +
>> +static const AVOption aecho_options[] = {
>> +    { "in_gain",  "", OFFSET(in_gain),  AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 1, A },
>> +    { "out_gain", "", OFFSET(out_gain), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 1, A },
>> +    { "delay1",   "", OFFSET(delay[0]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 90000, A },
>> +    { "decay1",   "", OFFSET(decay[0]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 1, A },
>> +    { "delay2",   "", OFFSET(delay[1]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 90000, A },
>> +    { "decay2",   "", OFFSET(decay[1]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 1, A },
>> +    { "delay3",   "", OFFSET(delay[2]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 90000, A },
>> +    { "decay3",   "", OFFSET(decay[2]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 1, A },
>> +    { "delay4",   "", OFFSET(delay[3]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 90000, A },
>> +    { "decay4",   "", OFFSET(decay[3]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 1, A },
>> +    { "delay5",   "", OFFSET(delay[4]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 90000, A },
>> +    { "decay5",   "", OFFSET(decay[4]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 1, A },
>> +    { "delay6",   "", OFFSET(delay[5]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 90000, A },
>> +    { "decay6",   "", OFFSET(decay[5]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 1, A },
>> +    { "delay7",   "", OFFSET(delay[6]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 90000, A },
>> +    { "decay7",   "", OFFSET(decay[6]), AV_OPT_TYPE_FLOAT, {.dbl=0}, 0,
> 1, A },
>> +    { NULL },
>> +};
>
> The default should be saner, i.e. users should be able to have an echo
> effect without specifying any options.
>
> [...]
>
> Rest LGTM from a non-programmer's point of view.
>
> Timothy
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