[pulseaudio-discuss] [PATCH] source: Deal with filter having more channels than the master

[Alexander E. Patrakov]

04.11.2015 14:48, arun at accosted.net wrote:
> From: Arun Raghavan <git at arunraghavan.net>
>
> Without this, we hit an assert because the channel count in
> new_reference (which was inherited from the master) is lower than the
> channel count of the filter.

I have looked.

I could not reproduce any assertion fail, but the original 
pa_cvolume_merge is clearly wrong if s->reference_volume and 
root_source->real_volume have channel maps where a shorter one is not 
the beginning of the other.

-- 
Alexander E. Patrakov

> ---
>   src/pulsecore/source.c | 18 ++++++++++++++----
>   1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/src/pulsecore/source.c b/src/pulsecore/source.c
> index b553a2d..f4b96ab 100644
> --- a/src/pulsecore/source.c
> +++ b/src/pulsecore/source.c
> @@ -1573,7 +1573,7 @@ void pa_source_set_volume(
>           bool send_msg,
>           bool save) {
>
> -    pa_cvolume new_reference_volume;
> +    pa_cvolume new_reference_volume, root_real_volume;
>       pa_source *root_source;
>
>       pa_source_assert_ref(s);
> @@ -1630,11 +1630,21 @@ void pa_source_set_volume(
>           /* Ok, let's determine the new real volume */
>           compute_real_volume(root_source);
>
> -        /* Let's 'push' the reference volume if necessary */
> -        pa_cvolume_merge(&new_reference_volume, &s->reference_volume, &root_source->real_volume);
> -        /* If the source and its root don't have the same number of channels, we need to remap */
> +        /* To propagate the reference volume from the filter to the root source,
> +         * we first take the real volume from the root source and remap it to
> +         * match the filter. Then, we merge in the reference volume from the
> +         * filter on top of this, and remap it back to the root source channel
> +         * count and map */
> +        root_real_volume = root_source->real_volume;
> +        /* First we remap root's real volume to filter channel count and map if needed */
> +        if (s != root_source && !pa_channel_map_equal(&s->channel_map, &root_source->channel_map))
> +            pa_cvolume_remap(&root_real_volume, &root_source->channel_map, &s->channel_map);
> +        /* Then let's 'push' the reference volume if necessary */
> +        pa_cvolume_merge(&new_reference_volume, &s->reference_volume, &root_real_volume);
> +        /* If the source and its root don't have the same number of channels, we need to remap back */
>           if (s != root_source && !pa_channel_map_equal(&s->channel_map, &root_source->channel_map))
>               pa_cvolume_remap(&new_reference_volume, &s->channel_map, &root_source->channel_map);
> +
>           update_reference_volume(root_source, &new_reference_volume, &root_source->channel_map, save);
>
>           /* Now that the reference volume is updated, we can update the streams'
>