/*
  * SMPTE 302M encoder
  * Copyright (c) 2010 Google, Inc.
  * Copyright (c) 2013 Darryl Wallace <wallacdj@gmail.com>
  *
  * 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
  * Lesser 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
  */
 
 #include "avcodec.h"
 #include "internal.h"

 #include "mathops.h"

 #include "put_bits.h"
 
 #define AES3_HEADER_LEN 4
 
 typedef struct S302MEncContext {
     uint8_t framing_index; /* Set for even channels on multiple of 192 samples */
 } S302MEncContext;
 
 static av_cold int s302m_encode_init(AVCodecContext *avctx)
 {
     S302MEncContext *s = avctx->priv_data;
 
     if (avctx->channels & 1 || avctx->channels > 8) {
         av_log(avctx, AV_LOG_ERROR,
                "Encoding %d channel(s) is not allowed. Only 2, 4, 6 and 8 channels are supported.\n",
                avctx->channels);
         return AVERROR(EINVAL);
     }
 
     switch (avctx->sample_fmt) {
     case AV_SAMPLE_FMT_S16:
         avctx->bits_per_raw_sample = 16;
         break;
     case AV_SAMPLE_FMT_S32:

         if (avctx->bits_per_raw_sample > 20) {

             if (avctx->bits_per_raw_sample > 24)

                 av_log(avctx, AV_LOG_WARNING, "encoding as 24 bits-per-sample\n");

             avctx->bits_per_raw_sample = 24;
         } else if (!avctx->bits_per_raw_sample) {
             avctx->bits_per_raw_sample = 24;
         } else if (avctx->bits_per_raw_sample <= 20) {
             avctx->bits_per_raw_sample = 20;
         }
     }
 
     avctx->frame_size = 0;
     avctx->bit_rate   = 48000 * avctx->channels *
                        (avctx->bits_per_raw_sample + 4);
     s->framing_index  = 0;
 
     return 0;
 }
 
 static int s302m_encode2_frame(AVCodecContext *avctx, AVPacket *avpkt,
                                const AVFrame *frame, int *got_packet_ptr)
 {
     S302MEncContext *s = avctx->priv_data;
     const int buf_size = AES3_HEADER_LEN +
                         (frame->nb_samples *
                          avctx->channels *
                         (avctx->bits_per_raw_sample + 4)) / 8;
     int ret, c, channels;
     uint8_t *o;
     PutBitContext pb;
 

     if (buf_size - AES3_HEADER_LEN > UINT16_MAX) {
         av_log(avctx, AV_LOG_ERROR, "number of samples in frame too big\n");
         return AVERROR(EINVAL);
     }
 

     if ((ret = ff_alloc_packet2(avctx, avpkt, buf_size, 0)) < 0)

         return ret;
 
     o = avpkt->data;

     init_put_bits(&pb, o, buf_size);

     put_bits(&pb, 16, buf_size - AES3_HEADER_LEN);
     put_bits(&pb, 2, (avctx->channels - 2) >> 1);   // number of channels
     put_bits(&pb, 8, 0);                            // channel ID
     put_bits(&pb, 2, (avctx->bits_per_raw_sample - 16) / 4); // bits per samples (0 = 16bit, 1 = 20bit, 2 = 24bit)
     put_bits(&pb, 4, 0);                            // alignments
     flush_put_bits(&pb);
     o += AES3_HEADER_LEN;
 
     if (avctx->bits_per_raw_sample == 24) {
         const uint32_t *samples = (uint32_t *)frame->data[0];
 
         for (c = 0; c < frame->nb_samples; c++) {
             uint8_t vucf = s->framing_index == 0 ? 0x10: 0;
 
             for (channels = 0; channels < avctx->channels; channels += 2) {
                 o[0] = ff_reverse[(samples[0] & 0x0000FF00) >> 8];
                 o[1] = ff_reverse[(samples[0] & 0x00FF0000) >> 16];
                 o[2] = ff_reverse[(samples[0] & 0xFF000000) >> 24];
                 o[3] = ff_reverse[(samples[1] & 0x00000F00) >> 4] | vucf;
                 o[4] = ff_reverse[(samples[1] & 0x000FF000) >> 12];
                 o[5] = ff_reverse[(samples[1] & 0x0FF00000) >> 20];
                 o[6] = ff_reverse[(samples[1] & 0xF0000000) >> 28];
                 o += 7;
                 samples += 2;
             }
 
             s->framing_index++;
             if (s->framing_index >= 192)
                 s->framing_index = 0;
         }
     } else if (avctx->bits_per_raw_sample == 20) {
         const uint32_t *samples = (uint32_t *)frame->data[0];
 
         for (c = 0; c < frame->nb_samples; c++) {
             uint8_t vucf = s->framing_index == 0 ? 0x80: 0;
 
             for (channels = 0; channels < avctx->channels; channels += 2) {
                 o[0] = ff_reverse[ (samples[0] & 0x000FF000) >> 12];
                 o[1] = ff_reverse[ (samples[0] & 0x0FF00000) >> 20];
                 o[2] = ff_reverse[((samples[0] & 0xF0000000) >> 28) | vucf];
                 o[3] = ff_reverse[ (samples[1] & 0x000FF000) >> 12];
                 o[4] = ff_reverse[ (samples[1] & 0x0FF00000) >> 20];
                 o[5] = ff_reverse[ (samples[1] & 0xF0000000) >> 28];
                 o += 6;
                 samples += 2;
             }
 
             s->framing_index++;
             if (s->framing_index >= 192)
                 s->framing_index = 0;
         }
     } else if (avctx->bits_per_raw_sample == 16) {
         const uint16_t *samples = (uint16_t *)frame->data[0];
 
         for (c = 0; c < frame->nb_samples; c++) {
             uint8_t vucf = s->framing_index == 0 ? 0x10 : 0;
 
             for (channels = 0; channels < avctx->channels; channels += 2) {
                 o[0] = ff_reverse[ samples[0] & 0xFF];
                 o[1] = ff_reverse[(samples[0] & 0xFF00) >>  8];
                 o[2] = ff_reverse[(samples[1] & 0x0F)   <<  4] | vucf;
                 o[3] = ff_reverse[(samples[1] & 0x0FF0) >>  4];
                 o[4] = ff_reverse[(samples[1] & 0xF000) >> 12];
                 o += 5;
                 samples += 2;
 
             }
 
             s->framing_index++;
             if (s->framing_index >= 192)
                 s->framing_index = 0;
         }
     }
 
     *got_packet_ptr = 1;
 
     return 0;
 }
 
 AVCodec ff_s302m_encoder = {
     .name                  = "s302m",

     .long_name             = NULL_IF_CONFIG_SMALL("SMPTE 302M"),

     .type                  = AVMEDIA_TYPE_AUDIO,

     .id                    = AV_CODEC_ID_S302M,

     .priv_data_size        = sizeof(S302MEncContext),
     .init                  = s302m_encode_init,
     .encode2               = s302m_encode2_frame,
     .sample_fmts           = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S32,
                                                             AV_SAMPLE_FMT_S16,
                                                             AV_SAMPLE_FMT_NONE },

     .capabilities          = AV_CODEC_CAP_VARIABLE_FRAME_SIZE | AV_CODEC_CAP_EXPERIMENTAL,

     .supported_samplerates = (const int[]) { 48000, 0 },

  /* .channel_layouts       = (const uint64_t[]) { AV_CH_LAYOUT_STEREO,

                                                   AV_CH_LAYOUT_QUAD,
                                                   AV_CH_LAYOUT_5POINT1_BACK,
                                                   AV_CH_LAYOUT_5POINT1_BACK | AV_CH_LAYOUT_STEREO_DOWNMIX,

                                                   0 }, */

 };