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Clarify the mixdown comments.

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This commit is contained in:
Mike Brady
2026-05-07 14:18:55 +01:00
parent a50eed043e
commit 4b020a6b22
1 changed files with 20 additions and 15 deletions
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player.c
+20 -15
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@@ -652,20 +652,25 @@ int setup_software_resampler(rtsp_conn_info *conn, ssrc_t ssrc) {
av_opt_set_sample_fmt(swr, "in_sample_fmt", input_format, 0);
// remember that if mixdown is enabled,
// set the resampler's channel layout either automatically or use the
// setting that has been given
// If mixdown is enabled, set the resampler's channel layout,
// either automatically based on the number of ooutput channels,
// or by using the setting that has been given.
// We impose the rule that, if the mixdown setting is "auto",
// we will not upmix if the number of output channels available
// is greater than the number of channels needed.
// To do an upmix, you will have to specify the upmix target, e.g. "7.1"
// in the mixdown setting.
// Upmixing will not be done if the setting is "auto".
// NOTE: upmixing at present, by default, simply copies the input channels to their
// equivalents in the output channel set. All the other channels are
// left alone.
// Similarly, on the "auto" setting, downmixing will be done
// only if the number of output channels available
// is strictly less than the number of input channels.
// If the number of output channels equals the number of input channels,
// no mixing is done on the "auto" setting.
// To do an upmix or a custom downmix, specify
// the target format, e.g. "7.1" in the mixdown setting.
// NOTE: upmixing, by default, simply copies the input channels to their
// equivalents in the output channels. All other channels are
// left silent.
#if LIBAVUTIL_VERSION_MAJOR >= 57
{
@@ -678,11 +683,11 @@ int setup_software_resampler(rtsp_conn_info *conn, ssrc_t ssrc) {
AVChannelLayout output_channel_layout;
if (config.mixdown_enable != 0) {
if (config.mixdown_channel_layout == 0) {
if (CHANNELS_FROM_ENCODED_FORMAT(output_configuration) > (unsigned) input_channel_count) {
av_channel_layout_from_mask(&output_channel_layout, input_layout);
} else {
if (CHANNELS_FROM_ENCODED_FORMAT(output_configuration) < (unsigned) input_channel_count) {
av_channel_layout_default(&output_channel_layout,
CHANNELS_FROM_ENCODED_FORMAT(output_configuration));
} else {
av_channel_layout_from_mask(&output_channel_layout, input_layout);
}
} else {
av_channel_layout_from_mask(&output_channel_layout, config.mixdown_channel_layout);