/*
  * Copyright (c) 2011 Nicolas George <nicolas.george@normalesup.org>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**
  * @file
  * Audio merging filter
  */
 
 #include "libswresample/swresample.h" // only for SWR_CH_MAX
 #include "avfilter.h"

 #include "audio.h"

 #include "internal.h"
 
 #define QUEUE_SIZE 16
 
 typedef struct {
     int nb_in_ch[2];       /**< number of channels for each input */
     int route[SWR_CH_MAX]; /**< channels routing, see copy_samples */
     int bps;
     struct amerge_queue {
         AVFilterBufferRef *buf[QUEUE_SIZE];
         int nb_buf, nb_samples, pos;
     } queue[2];
 } AMergeContext;
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     AMergeContext *am = ctx->priv;
     int i, j;
 
     for (i = 0; i < 2; i++)
         for (j = 0; j < am->queue[i].nb_buf; j++)
             avfilter_unref_buffer(am->queue[i].buf[j]);
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     AMergeContext *am = ctx->priv;
     int64_t inlayout[2], outlayout;
     AVFilterFormats *formats;

     AVFilterChannelLayouts *layouts;

     int i;
 
     for (i = 0; i < 2; i++) {

         if (!ctx->inputs[i]->in_channel_layouts ||
             !ctx->inputs[i]->in_channel_layouts->nb_channel_layouts) {

             av_log(ctx, AV_LOG_ERROR,
                    "No channel layout for input %d\n", i + 1);
             return AVERROR(EINVAL);
         }

         inlayout[i] = ctx->inputs[i]->in_channel_layouts->channel_layouts[0];
         if (ctx->inputs[i]->in_channel_layouts->nb_channel_layouts > 1) {

             char buf[256];
             av_get_channel_layout_string(buf, sizeof(buf), 0, inlayout[i]);
             av_log(ctx, AV_LOG_INFO, "Using \"%s\" for input %d\n", buf, i + 1);
         }
         am->nb_in_ch[i] = av_get_channel_layout_nb_channels(inlayout[i]);
     }
     if (am->nb_in_ch[0] + am->nb_in_ch[1] > SWR_CH_MAX) {
         av_log(ctx, AV_LOG_ERROR, "Too many channels (max %d)\n", SWR_CH_MAX);
         return AVERROR(EINVAL);
     }
     if (inlayout[0] & inlayout[1]) {
         av_log(ctx, AV_LOG_WARNING,
                "Inputs overlap: output layout will be meaningless\n");
         for (i = 0; i < am->nb_in_ch[0] + am->nb_in_ch[1]; i++)
             am->route[i] = i;
         outlayout = av_get_default_channel_layout(am->nb_in_ch[0] +
                                                   am->nb_in_ch[1]);
         if (!outlayout)
             outlayout = ((int64_t)1 << (am->nb_in_ch[0] + am->nb_in_ch[1])) - 1;
     } else {
         int *route[2] = { am->route, am->route + am->nb_in_ch[0] };
         int c, out_ch_number = 0;
 
         outlayout = inlayout[0] | inlayout[1];
         for (c = 0; c < 64; c++)
             for (i = 0; i < 2; i++)
                 if ((inlayout[i] >> c) & 1)
                     *(route[i]++) = out_ch_number++;
     }

     formats = avfilter_make_format_list(ff_packed_sample_fmts);

     avfilter_set_common_sample_formats(ctx, formats);
     for (i = 0; i < 2; i++) {

         layouts = NULL;
         ff_add_channel_layout(&layouts, inlayout[i]);
         ff_channel_layouts_ref(layouts, &ctx->inputs[i]->out_channel_layouts);

     }

     layouts = NULL;
     ff_add_channel_layout(&layouts, outlayout);
     ff_channel_layouts_ref(layouts, &ctx->outputs[0]->in_channel_layouts);

     ff_set_common_samplerates(ctx, ff_all_samplerates());

     return 0;
 }
 
 static int config_output(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     AMergeContext *am = ctx->priv;
     int64_t layout;
     char name[3][256];
     int i;
 
     if (ctx->inputs[0]->sample_rate != ctx->inputs[1]->sample_rate) {
         av_log(ctx, AV_LOG_ERROR,
                "Inputs must have the same sample rate "
                "(%"PRIi64" vs %"PRIi64")\n",
                ctx->inputs[0]->sample_rate, ctx->inputs[1]->sample_rate);
         return AVERROR(EINVAL);
     }
     am->bps = av_get_bytes_per_sample(ctx->outputs[0]->format);
     outlink->sample_rate = ctx->inputs[0]->sample_rate;
     outlink->time_base   = ctx->inputs[0]->time_base;
     for (i = 0; i < 3; i++) {
         layout = (i < 2 ? ctx->inputs[i] : ctx->outputs[0])->channel_layout;
         av_get_channel_layout_string(name[i], sizeof(name[i]), -1, layout);
     }
     av_log(ctx, AV_LOG_INFO,
            "in1:%s + in2:%s -> out:%s\n", name[0], name[1], name[2]);
     return 0;
 }
 
 static int request_frame(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;
     AMergeContext *am = ctx->priv;

     int i, ret;

 
     for (i = 0; i < 2; i++)
         if (!am->queue[i].nb_samples)

             if ((ret = avfilter_request_frame(ctx->inputs[i])) < 0)
                 return ret;

     return 0;
 }
 
 /**
  * Copy samples from two input streams to one output stream.
  * @param nb_in_ch  number of channels in each input stream
  * @param route     routing values;
  *                  input channel i goes to output channel route[i];
  *                  i <  nb_in_ch[0] are the channels from the first output;
  *                  i >= nb_in_ch[0] are the channels from the second output
  * @param ins       pointer to the samples of each inputs, in packed format;
  *                  will be left at the end of the copied samples
  * @param outs      pointer to the samples of the output, in packet format;
  *                  must point to a buffer big enough;
  *                  will be left at the end of the copied samples
  * @param ns        number of samples to copy
  * @param bps       bytes per sample
  */
 static inline void copy_samples(int nb_in_ch[2], int *route, uint8_t *ins[2],
                                 uint8_t **outs, int ns, int bps)
 {
     int *route_cur;
     int i, c;
 
     while (ns--) {
         route_cur = route;
         for (i = 0; i < 2; i++) {
             for (c = 0; c < nb_in_ch[i]; c++) {
                 memcpy((*outs) + bps * *(route_cur++), ins[i], bps);
                 ins[i] += bps;
             }
         }
         *outs += (nb_in_ch[0] + nb_in_ch[1]) * bps;
     }
 }
 
 static void filter_samples(AVFilterLink *inlink, AVFilterBufferRef *insamples)
 {
     AVFilterContext *ctx = inlink->dst;
     AMergeContext *am = ctx->priv;

     AVFilterLink *const outlink = ctx->outputs[0];

     int input_number = inlink == ctx->inputs[1];
     struct amerge_queue *inq = &am->queue[input_number];
     int nb_samples, ns, i;
     AVFilterBufferRef *outbuf, **inbuf[2];
     uint8_t *ins[2], *outs;
 
     if (inq->nb_buf == QUEUE_SIZE) {
         av_log(ctx, AV_LOG_ERROR, "Packet queue overflow; dropped\n");
         avfilter_unref_buffer(insamples);
         return;
     }
     inq->buf[inq->nb_buf++] = avfilter_ref_buffer(insamples, AV_PERM_READ |
                                                              AV_PERM_PRESERVE);
     inq->nb_samples += insamples->audio->nb_samples;
     avfilter_unref_buffer(insamples);
     if (!am->queue[!input_number].nb_samples)
         return;
 
     nb_samples = FFMIN(am->queue[0].nb_samples,
                        am->queue[1].nb_samples);

     outbuf = ff_get_audio_buffer(ctx->outputs[0], AV_PERM_WRITE,

                                        nb_samples);
     outs = outbuf->data[0];
     for (i = 0; i < 2; i++) {
         inbuf[i] = am->queue[i].buf;
         ins[i] = (*inbuf[i])->data[0] +
                  am->queue[i].pos * am->nb_in_ch[i] * am->bps;
     }

     outbuf->pts = (*inbuf[0])->pts == AV_NOPTS_VALUE ? AV_NOPTS_VALUE :
                   (*inbuf[0])->pts +
                   av_rescale_q(am->queue[0].pos,
                                (AVRational){ 1, ctx->inputs[0]->sample_rate },
                                ctx->outputs[0]->time_base);

 
     avfilter_copy_buffer_ref_props(outbuf, *inbuf[0]);
     outbuf->audio->nb_samples     = nb_samples;
     outbuf->audio->channel_layout = outlink->channel_layout;
 

     while (nb_samples) {
         ns = nb_samples;
         for (i = 0; i < 2; i++)
             ns = FFMIN(ns, (*inbuf[i])->audio->nb_samples - am->queue[i].pos);
         /* Unroll the most common sample formats: speed +~350% for the loop,
            +~13% overall (including two common decoders) */
         switch (am->bps) {
             case 1:
                 copy_samples(am->nb_in_ch, am->route, ins, &outs, ns, 1);
                 break;
             case 2:
                 copy_samples(am->nb_in_ch, am->route, ins, &outs, ns, 2);
                 break;
             case 4:
                 copy_samples(am->nb_in_ch, am->route, ins, &outs, ns, 4);
                 break;
             default:
                 copy_samples(am->nb_in_ch, am->route, ins, &outs, ns, am->bps);
                 break;
         }
 
         nb_samples -= ns;
         for (i = 0; i < 2; i++) {
             am->queue[i].nb_samples -= ns;
             am->queue[i].pos += ns;
             if (am->queue[i].pos == (*inbuf[i])->audio->nb_samples) {
                 am->queue[i].pos = 0;
                 avfilter_unref_buffer(*inbuf[i]);
                 *inbuf[i] = NULL;
                 inbuf[i]++;
                 ins[i] = *inbuf[i] ? (*inbuf[i])->data[0] : NULL;
             }
         }
     }
     for (i = 0; i < 2; i++) {
         int nbufused = inbuf[i] - am->queue[i].buf;
         if (nbufused) {
             am->queue[i].nb_buf -= nbufused;
             memmove(am->queue[i].buf, inbuf[i],
                     am->queue[i].nb_buf * sizeof(**inbuf));
         }
     }

     ff_filter_samples(ctx->outputs[0], outbuf);

 }
 
 AVFilter avfilter_af_amerge = {
     .name          = "amerge",
     .description   = NULL_IF_CONFIG_SMALL("Merge two audio streams into "
                                           "a single multi-channel stream."),
     .priv_size     = sizeof(AMergeContext),
     .uninit        = uninit,
     .query_formats = query_formats,
 
     .inputs    = (const AVFilterPad[]) {
         { .name             = "in1",
           .type             = AVMEDIA_TYPE_AUDIO,
           .filter_samples   = filter_samples,
           .min_perms        = AV_PERM_READ, },
         { .name             = "in2",
           .type             = AVMEDIA_TYPE_AUDIO,
           .filter_samples   = filter_samples,
           .min_perms        = AV_PERM_READ, },
         { .name = NULL }
     },
     .outputs   = (const AVFilterPad[]) {
         { .name             = "default",
           .type             = AVMEDIA_TYPE_AUDIO,
           .config_props     = config_output,
           .request_frame    = request_frame, },
         { .name = NULL }
     },
 };