diff options
| -rw-r--r-- | doc/filters.texi | 6 | ||||
| -rw-r--r-- | libavfilter/af_amix.c | 13 |
2 files changed, 16 insertions, 3 deletions
diff --git a/doc/filters.texi b/doc/filters.texi index 2d85a414ec..52bced3143 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -1879,6 +1879,11 @@ stream ends. The default value is 2 seconds. @item weights Specify weight of each input audio stream as sequence. Each weight is separated by space. By default all inputs have same weight. + +@item sum +Do not scale inputs but instead do only summation of samples. +Beware of heavy clipping if inputs are not normalized prior of filtering +or output from @var{amix} normalized after filtering. By default is disabled. @end table @subsection Commands @@ -1886,6 +1891,7 @@ Each weight is separated by space. By default all inputs have same weight. This filter supports the following commands: @table @option @item weights +@item sum Syntax is same as option with same name. @end table diff --git a/libavfilter/af_amix.c b/libavfilter/af_amix.c index c4d8916a57..beaf7bcada 100644 --- a/libavfilter/af_amix.c +++ b/libavfilter/af_amix.c @@ -164,6 +164,7 @@ typedef struct MixContext { int duration_mode; /**< mode for determining duration */ float dropout_transition; /**< transition time when an input drops out */ char *weights_str; /**< string for custom weights for every input */ + int sum; /**< inputs are not scaled, only added */ int nb_channels; /**< number of channels */ int sample_rate; /**< sample rate */ @@ -195,6 +196,8 @@ static const AVOption amix_options[] = { OFFSET(dropout_transition), AV_OPT_TYPE_FLOAT, { .dbl = 2.0 }, 0, INT_MAX, A|F }, { "weights", "Set weight for each input.", OFFSET(weights_str), AV_OPT_TYPE_STRING, {.str="1 1"}, 0, 0, A|F|T }, + { "sum", "Do not scale inputs instead do only sum", + OFFSET(sum), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, A|F|T }, { NULL } }; @@ -227,10 +230,14 @@ static void calculate_scales(MixContext *s, int nb_samples) } for (i = 0; i < s->nb_inputs; i++) { - if (s->input_state[i] & INPUT_ON) - s->input_scale[i] = 1.0f / s->scale_norm[i] * FFSIGN(s->weights[i]); - else + if (s->input_state[i] & INPUT_ON) { + if (s->sum) + s->input_scale[i] = 1.0f; + else + s->input_scale[i] = 1.0f / s->scale_norm[i] * FFSIGN(s->weights[i]); + } else { s->input_scale[i] = 0.0f; + } } } |