diff --git a/doc/filters.texi b/doc/filters.texi index d6ea56b851..870c50441b 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -2208,8 +2208,17 @@ It accepts the following parameters: @table @option @item channel_layout The channel layout of the input stream. The default is "stereo". +@item channels +A channel layout describing the channels to be extracted as separate output streams +or "all" to extract each input channel as a separate stream. The default is "all". + +Choosing channels not present in channel layout in the input will result in an error. @end table +@subsection Examples + +@itemize +@item For example, assuming a stereo input MP3 file, @example ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv @@ -2217,6 +2226,7 @@ ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv will create an output Matroska file with two audio streams, one containing only the left channel and the other the right channel. +@item Split a 5.1 WAV file into per-channel files: @example ffmpeg -i in.wav -filter_complex @@ -2226,6 +2236,14 @@ front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]' side_right.wav @end example +@item +Extract only LFE from a 5.1 WAV file: +@example +ffmpeg -i in.wav -filter_complex 'channelsplit=channel_layout=5.1:channels=LFE[LFE]' +-map '[LFE]' lfe.wav +@end example +@end itemize + @section chorus Add a chorus effect to the audio. diff --git a/libavfilter/af_channelsplit.c b/libavfilter/af_channelsplit.c index 8c6b00fe4f..821bb73801 100644 --- a/libavfilter/af_channelsplit.c +++ b/libavfilter/af_channelsplit.c @@ -38,6 +38,9 @@ typedef struct ChannelSplitContext { uint64_t channel_layout; char *channel_layout_str; + char *channels_str; + + int map[64]; } ChannelSplitContext; #define OFFSET(x) offsetof(ChannelSplitContext, x) @@ -45,6 +48,7 @@ typedef struct ChannelSplitContext { #define F AV_OPT_FLAG_FILTERING_PARAM static const AVOption channelsplit_options[] = { { "channel_layout", "Input channel layout.", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, { .str = "stereo" }, .flags = A|F }, + { "channels", "Channels to extract.", OFFSET(channels_str), AV_OPT_TYPE_STRING, { .str = "all" }, .flags = A|F }, { NULL } }; @@ -53,8 +57,9 @@ AVFILTER_DEFINE_CLASS(channelsplit); static av_cold int init(AVFilterContext *ctx) { ChannelSplitContext *s = ctx->priv; + uint64_t channel_layout; int nb_channels; - int ret = 0, i; + int all = 0, ret = 0, i; if (!(s->channel_layout = av_get_channel_layout(s->channel_layout_str))) { av_log(ctx, AV_LOG_ERROR, "Error parsing channel layout '%s'.\n", @@ -63,14 +68,35 @@ static av_cold int init(AVFilterContext *ctx) goto fail; } - nb_channels = av_get_channel_layout_nb_channels(s->channel_layout); + + if (!strcmp(s->channels_str, "all")) { + nb_channels = av_get_channel_layout_nb_channels(s->channel_layout); + channel_layout = s->channel_layout; + all = 1; + } else { + if ((ret = av_get_extended_channel_layout(s->channels_str, &channel_layout, &nb_channels)) < 0) + return ret; + } + for (i = 0; i < nb_channels; i++) { - uint64_t channel = av_channel_layout_extract_channel(s->channel_layout, i); + uint64_t channel = av_channel_layout_extract_channel(channel_layout, i); AVFilterPad pad = { 0 }; pad.type = AVMEDIA_TYPE_AUDIO; pad.name = av_get_channel_name(channel); + if (all) { + s->map[i] = i; + } else { + if ((ret = av_get_channel_layout_channel_index(s->channel_layout, channel)) < 0) { + av_log(ctx, AV_LOG_ERROR, "Channel name '%s' not present in channel layout '%s'.\n", + av_get_channel_name(channel), s->channel_layout_str); + return ret; + } + + s->map[i] = ret; + } + if ((ret = ff_insert_outpad(ctx, i, &pad)) < 0) { return ret; } @@ -96,7 +122,7 @@ static int query_formats(AVFilterContext *ctx) for (i = 0; i < ctx->nb_outputs; i++) { AVFilterChannelLayouts *out_layouts = NULL; - uint64_t channel = av_channel_layout_extract_channel(s->channel_layout, i); + uint64_t channel = av_channel_layout_extract_channel(s->channel_layout, s->map[i]); if ((ret = ff_add_channel_layout(&out_layouts, channel)) < 0 || (ret = ff_channel_layouts_ref(out_layouts, &ctx->outputs[i]->in_channel_layouts)) < 0) @@ -109,6 +135,7 @@ static int query_formats(AVFilterContext *ctx) static int filter_frame(AVFilterLink *inlink, AVFrame *buf) { AVFilterContext *ctx = inlink->dst; + ChannelSplitContext *s = ctx->priv; int i, ret = 0; for (i = 0; i < ctx->nb_outputs; i++) { @@ -119,9 +146,9 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *buf) break; } - buf_out->data[0] = buf_out->extended_data[0] = buf_out->extended_data[i]; + buf_out->data[0] = buf_out->extended_data[0] = buf_out->extended_data[s->map[i]]; buf_out->channel_layout = - av_channel_layout_extract_channel(buf->channel_layout, i); + av_channel_layout_extract_channel(buf->channel_layout, s->map[i]); buf_out->channels = 1; ret = ff_filter_frame(ctx->outputs[i], buf_out);