The macro can be used to define consistently the internal class of a filter, save some typing and factorize.
		
			
				
	
	
		
			142 lines
		
	
	
		
			4.4 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			142 lines
		
	
	
		
			4.4 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
| /*
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|  * This file is part of Libav.
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|  *
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|  * Libav is free software; you can redistribute it and/or
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|  * modify it under the terms of the GNU Lesser General Public
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|  * License as published by the Free Software Foundation; either
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|  * version 2.1 of the License, or (at your option) any later version.
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|  *
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|  * Libav is distributed in the hope that it will be useful,
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|  * but WITHOUT ANY WARRANTY; without even the implied warranty of
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|  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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|  * Lesser General Public License for more details.
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|  *
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|  * You should have received a copy of the GNU Lesser General Public
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|  * License along with Libav; if not, write to the Free Software
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|  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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|  */
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| 
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| /**
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|  * @file
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|  * Channel split filter
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|  *
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|  * Split an audio stream into per-channel streams.
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|  */
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| 
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| #include "libavutil/audioconvert.h"
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| #include "libavutil/opt.h"
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| 
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| #include "audio.h"
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| #include "avfilter.h"
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| #include "formats.h"
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| #include "internal.h"
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| 
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| typedef struct ChannelSplitContext {
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|     const AVClass *class;
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| 
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|     uint64_t channel_layout;
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|     char    *channel_layout_str;
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| } ChannelSplitContext;
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| 
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| #define OFFSET(x) offsetof(ChannelSplitContext, x)
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| #define A AV_OPT_FLAG_AUDIO_PARAM
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| static const AVOption channelsplit_options[] = {
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|     { "channel_layout", "Input channel layout.", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, { .str = "stereo" }, .flags = A },
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|     { NULL },
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| };
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| 
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| AVFILTER_DEFINE_CLASS(channelsplit);
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| 
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| static int init(AVFilterContext *ctx, const char *arg, void *opaque)
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| {
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|     ChannelSplitContext *s = ctx->priv;
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|     int nb_channels;
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|     int ret = 0, i;
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| 
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|     s->class = &channelsplit_class;
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|     av_opt_set_defaults(s);
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|     if ((ret = av_set_options_string(s, arg, "=", ":")) < 0) {
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|         av_log(ctx, AV_LOG_ERROR, "Error parsing options string '%s'.\n", arg);
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|         return ret;
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|     }
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|     if (!(s->channel_layout = av_get_channel_layout(s->channel_layout_str))) {
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|         av_log(ctx, AV_LOG_ERROR, "Error parsing channel layout '%s'.\n",
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|                s->channel_layout_str);
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|         ret = AVERROR(EINVAL);
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|         goto fail;
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|     }
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| 
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|     nb_channels = av_get_channel_layout_nb_channels(s->channel_layout);
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|     for (i = 0; i < nb_channels; i++) {
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|         uint64_t channel = av_channel_layout_extract_channel(s->channel_layout, i);
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|         AVFilterPad pad  = { 0 };
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| 
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|         pad.type = AVMEDIA_TYPE_AUDIO;
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|         pad.name = av_get_channel_name(channel);
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| 
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|         ff_insert_outpad(ctx, i, &pad);
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|     }
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| 
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| fail:
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|     av_opt_free(s);
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|     return ret;
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| }
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| 
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| static int query_formats(AVFilterContext *ctx)
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| {
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|     ChannelSplitContext *s = ctx->priv;
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|     AVFilterChannelLayouts *in_layouts = NULL;
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|     int i;
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| 
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|     ff_set_common_formats    (ctx, ff_planar_sample_fmts());
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|     ff_set_common_samplerates(ctx, ff_all_samplerates());
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| 
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|     ff_add_channel_layout(&in_layouts, s->channel_layout);
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|     ff_channel_layouts_ref(in_layouts, &ctx->inputs[0]->out_channel_layouts);
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| 
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|     for (i = 0; i < ctx->nb_outputs; i++) {
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|         AVFilterChannelLayouts *out_layouts = NULL;
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|         uint64_t channel = av_channel_layout_extract_channel(s->channel_layout, i);
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| 
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|         ff_add_channel_layout(&out_layouts, channel);
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|         ff_channel_layouts_ref(out_layouts, &ctx->outputs[i]->in_channel_layouts);
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|     }
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| 
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|     return 0;
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| }
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| 
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| static void filter_samples(AVFilterLink *inlink, AVFilterBufferRef *buf)
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| {
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|     AVFilterContext *ctx = inlink->dst;
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|     int i;
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| 
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|     for (i = 0; i < ctx->nb_outputs; i++) {
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|         AVFilterBufferRef *buf_out = avfilter_ref_buffer(buf, ~AV_PERM_WRITE);
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| 
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|         if (!buf_out)
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|             return;
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| 
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|         buf_out->data[0] = buf_out->extended_data[0] = buf_out->extended_data[i];
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|         buf_out->audio->channel_layout =
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|             av_channel_layout_extract_channel(buf->audio->channel_layout, i);
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| 
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|         ff_filter_samples(ctx->outputs[i], buf_out);
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|     }
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|     avfilter_unref_buffer(buf);
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| }
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| 
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| AVFilter avfilter_af_channelsplit = {
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|     .name           = "channelsplit",
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|     .description    = NULL_IF_CONFIG_SMALL("Split audio into per-channel streams"),
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|     .priv_size      = sizeof(ChannelSplitContext),
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| 
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|     .init           = init,
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|     .query_formats  = query_formats,
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| 
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|     .inputs  = (const AVFilterPad[]){{ .name           = "default",
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|                                        .type           = AVMEDIA_TYPE_AUDIO,
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|                                        .filter_samples = filter_samples, },
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|                                      { NULL }},
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|     .outputs = (const AVFilterPad[]){{ NULL }},
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| };
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