/*
  * Digital Speech Standard (DSS) demuxer
  * Copyright (c) 2014 Oleksij Rempel <linux@rempel-privat.de>
  *

  * 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 "libavutil/attributes.h"
 #include "libavutil/bswap.h"
 #include "libavutil/channel_layout.h"
 #include "libavutil/intreadwrite.h"
 
 #include "avformat.h"
 #include "internal.h"
 
 #define DSS_HEAD_OFFSET_AUTHOR        0xc
 #define DSS_AUTHOR_SIZE               16
 
 #define DSS_HEAD_OFFSET_START_TIME    0x26
 #define DSS_HEAD_OFFSET_END_TIME      0x32
 #define DSS_TIME_SIZE                 12
 
 #define DSS_HEAD_OFFSET_ACODEC        0x2a4
 #define DSS_ACODEC_DSS_SP             0x0    /* SP mode */
 #define DSS_ACODEC_G723_1             0x2    /* LP mode */
 
 #define DSS_HEAD_OFFSET_COMMENT       0x31e
 #define DSS_COMMENT_SIZE              64
 
 #define DSS_BLOCK_SIZE                512
 #define DSS_HEADER_SIZE              (DSS_BLOCK_SIZE * 2)
 #define DSS_AUDIO_BLOCK_HEADER_SIZE   6
 #define DSS_FRAME_SIZE                42
 
 static const uint8_t frame_size[4] = { 24, 20, 4, 1 };
 
 typedef struct DSSDemuxContext {
     unsigned int audio_codec;
     int counter;
     int swap;
     int dss_sp_swap_byte;
     int8_t *dss_sp_buf;

 
     int packet_size;

 } DSSDemuxContext;
 
 static int dss_probe(AVProbeData *p)
 {
     if (AV_RL32(p->buf) != MKTAG(0x2, 'd', 's', 's'))
         return 0;
 
     return AVPROBE_SCORE_MAX;
 }
 
 static int dss_read_metadata_date(AVFormatContext *s, unsigned int offset,
                                   const char *key)
 {
     AVIOContext *pb = s->pb;
     char datetime[64], string[DSS_TIME_SIZE + 1] = { 0 };
     int y, month, d, h, minute, sec;
     int ret;
 
     avio_seek(pb, offset, SEEK_SET);
 
     ret = avio_read(s->pb, string, DSS_TIME_SIZE);
     if (ret < DSS_TIME_SIZE)
         return ret < 0 ? ret : AVERROR_EOF;
 

     if (sscanf(string, "%2d%2d%2d%2d%2d%2d", &y, &month, &d, &h, &minute, &sec) != 6)
         return AVERROR_INVALIDDATA;

     /* We deal with a two-digit year here, so set the default date to 2000
      * and hope it will never be used in the next century. */
     snprintf(datetime, sizeof(datetime), "%.4d-%.2d-%.2dT%.2d:%.2d:%.2d",
              y + 2000, month, d, h, minute, sec);
     return av_dict_set(&s->metadata, key, datetime, 0);
 }
 
 static int dss_read_metadata_string(AVFormatContext *s, unsigned int offset,
                                     unsigned int size, const char *key)
 {
     AVIOContext *pb = s->pb;
     char *value;
     int ret;
 
     avio_seek(pb, offset, SEEK_SET);
 
     value = av_mallocz(size + 1);
     if (!value)
         return AVERROR(ENOMEM);
 
     ret = avio_read(s->pb, value, size);
     if (ret < size) {
         ret = ret < 0 ? ret : AVERROR_EOF;
         goto exit;
     }
 
     ret = av_dict_set(&s->metadata, key, value, 0);
 
 exit:
     av_free(value);
     return ret;
 }
 
 static int dss_read_header(AVFormatContext *s)
 {
     DSSDemuxContext *ctx = s->priv_data;
     AVIOContext *pb = s->pb;
     AVStream *st;
     int ret;
 
     st = avformat_new_stream(s, NULL);
     if (!st)
         return AVERROR(ENOMEM);
 
     ret = dss_read_metadata_string(s, DSS_HEAD_OFFSET_AUTHOR,
                                    DSS_AUTHOR_SIZE, "author");
     if (ret)
         return ret;
 
     ret = dss_read_metadata_date(s, DSS_HEAD_OFFSET_END_TIME, "date");
     if (ret)
         return ret;
 
     ret = dss_read_metadata_string(s, DSS_HEAD_OFFSET_COMMENT,
                                    DSS_COMMENT_SIZE, "comment");
     if (ret)
         return ret;
 
     avio_seek(pb, DSS_HEAD_OFFSET_ACODEC, SEEK_SET);
     ctx->audio_codec = avio_r8(pb);
 
     if (ctx->audio_codec == DSS_ACODEC_DSS_SP) {
         st->codec->codec_id    = AV_CODEC_ID_DSS_SP;

         st->codec->sample_rate = 11025;

     } else if (ctx->audio_codec == DSS_ACODEC_G723_1) {
         st->codec->codec_id    = AV_CODEC_ID_G723_1;
         st->codec->sample_rate = 8000;
     } else {
         avpriv_request_sample(s, "Support for codec %x in DSS",
                               ctx->audio_codec);
         return AVERROR_PATCHWELCOME;
     }
 
     st->codec->codec_type     = AVMEDIA_TYPE_AUDIO;
     st->codec->channel_layout = AV_CH_LAYOUT_MONO;
     st->codec->channels       = 1;
 
     avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
     st->start_time = 0;
 
     /* Jump over header */
 
     if (avio_seek(pb, DSS_HEADER_SIZE, SEEK_SET) != DSS_HEADER_SIZE)
         return AVERROR(EIO);
 
     ctx->counter = 0;
     ctx->swap    = 0;
 
     ctx->dss_sp_buf = av_malloc(DSS_FRAME_SIZE + 1);
     if (!ctx->dss_sp_buf)
         return AVERROR(ENOMEM);
 
     return 0;
 }
 
 static void dss_skip_audio_header(AVFormatContext *s, AVPacket *pkt)
 {
     DSSDemuxContext *ctx = s->priv_data;
     AVIOContext *pb = s->pb;
 
     avio_skip(pb, DSS_AUDIO_BLOCK_HEADER_SIZE);
     ctx->counter += DSS_BLOCK_SIZE - DSS_AUDIO_BLOCK_HEADER_SIZE;
 }
 
 static void dss_sp_byte_swap(DSSDemuxContext *ctx,
                              uint8_t *dst, const uint8_t *src)
 {
     int i;
 
     if (ctx->swap) {
         for (i = 3; i < DSS_FRAME_SIZE; i += 2)
             dst[i] = src[i];
 
         for (i = 0; i < DSS_FRAME_SIZE - 2; i += 2)
             dst[i] = src[i + 4];
 
         dst[1] = ctx->dss_sp_swap_byte;
     } else {
         memcpy(dst, src, DSS_FRAME_SIZE);
         ctx->dss_sp_swap_byte = src[DSS_FRAME_SIZE - 2];
     }
 
     /* make sure byte 40 is always 0 */
     dst[DSS_FRAME_SIZE - 2] = 0;
     ctx->swap             ^= 1;
 }
 
 static int dss_sp_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     DSSDemuxContext *ctx = s->priv_data;

     AVStream *st = s->streams[0];

     int read_size, ret, offset = 0, buff_offset = 0;

     int64_t pos = avio_tell(s->pb);

 
     if (ctx->counter == 0)
         dss_skip_audio_header(s, pkt);
 
     if (ctx->swap) {
         read_size   = DSS_FRAME_SIZE - 2;
         buff_offset = 3;
     } else
         read_size = DSS_FRAME_SIZE;
 
     ctx->counter -= read_size;

     ctx->packet_size = DSS_FRAME_SIZE - 1;

 
     ret = av_new_packet(pkt, DSS_FRAME_SIZE);
     if (ret < 0)
         return ret;
 

     pkt->duration     = 264;

     pkt->pos = pos;

     pkt->stream_index = 0;

     s->bit_rate = 8LL * ctx->packet_size * st->codec->sample_rate * 512 / (506 * pkt->duration);

 
     if (ctx->counter < 0) {
         int size2 = ctx->counter + read_size;
 
         ret = avio_read(s->pb, ctx->dss_sp_buf + offset + buff_offset,
                         size2 - offset);
         if (ret < size2 - offset)
             goto error_eof;
 
         dss_skip_audio_header(s, pkt);
         offset = size2;
     }
 
     ret = avio_read(s->pb, ctx->dss_sp_buf + offset + buff_offset,
                     read_size - offset);
     if (ret < read_size - offset)
         goto error_eof;
 
     dss_sp_byte_swap(ctx, pkt->data, ctx->dss_sp_buf);
 

     if (ctx->dss_sp_swap_byte < 0) {
         ret = AVERROR(EAGAIN);
         goto error_eof;
     }
 

     if (pkt->data[0] == 0xff)
         return AVERROR_INVALIDDATA;
 
     return pkt->size;
 
 error_eof:

     av_packet_unref(pkt);

     return ret < 0 ? ret : AVERROR_EOF;
 }
 
 static int dss_723_1_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     DSSDemuxContext *ctx = s->priv_data;

     AVStream *st = s->streams[0];

     int size, byte, ret, offset;

     int64_t pos = avio_tell(s->pb);

 
     if (ctx->counter == 0)
         dss_skip_audio_header(s, pkt);
 
     /* We make one byte-step here. Don't forget to add offset. */
     byte = avio_r8(s->pb);
     if (byte == 0xff)
         return AVERROR_INVALIDDATA;
 
     size = frame_size[byte & 3];
 

     ctx->packet_size = size;

     ctx->counter -= size;
 
     ret = av_new_packet(pkt, size);
     if (ret < 0)
         return ret;

     pkt->pos = pos;

 
     pkt->data[0]  = byte;
     offset        = 1;
     pkt->duration = 240;

     s->bit_rate = 8LL * size * st->codec->sample_rate * 512 / (506 * pkt->duration);

 
     pkt->stream_index = 0;
 
     if (ctx->counter < 0) {
         int size2 = ctx->counter + size;
 
         ret = avio_read(s->pb, pkt->data + offset,
                         size2 - offset);
         if (ret < size2 - offset) {

             av_packet_unref(pkt);

             return ret < 0 ? ret : AVERROR_EOF;
         }
 
         dss_skip_audio_header(s, pkt);
         offset = size2;
     }
 
     ret = avio_read(s->pb, pkt->data + offset, size - offset);
     if (ret < size - offset) {

         av_packet_unref(pkt);

         return ret < 0 ? ret : AVERROR_EOF;
     }
 
     return pkt->size;
 }
 
 static int dss_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     DSSDemuxContext *ctx = s->priv_data;
 
     if (ctx->audio_codec == DSS_ACODEC_DSS_SP)
         return dss_sp_read_packet(s, pkt);
     else
         return dss_723_1_read_packet(s, pkt);
 }
 
 static int dss_read_close(AVFormatContext *s)
 {
     DSSDemuxContext *ctx = s->priv_data;
 

     av_freep(&ctx->dss_sp_buf);

 
     return 0;
 }
 

 static int dss_read_seek(AVFormatContext *s, int stream_index,
                          int64_t timestamp, int flags)
 {
     DSSDemuxContext *ctx = s->priv_data;
     int64_t ret, seekto;
     uint8_t header[DSS_AUDIO_BLOCK_HEADER_SIZE];
     int offset;
 
     if (ctx->audio_codec == DSS_ACODEC_DSS_SP)
         seekto = timestamp / 264 * 41 / 506 * 512;
     else
         seekto = timestamp / 240 * ctx->packet_size / 506 * 512;
 
     if (seekto < 0)
         seekto = 0;
 
     seekto += DSS_HEADER_SIZE;
 
     ret = avio_seek(s->pb, seekto, SEEK_SET);
     if (ret < 0)
         return ret;
 
     avio_read(s->pb, header, DSS_AUDIO_BLOCK_HEADER_SIZE);
     ctx->swap = !!(header[0] & 0x80);
     offset = 2*header[1] + 2*ctx->swap;
     if (offset < DSS_AUDIO_BLOCK_HEADER_SIZE)
         return AVERROR_INVALIDDATA;
     if (offset == DSS_AUDIO_BLOCK_HEADER_SIZE) {
         ctx->counter = 0;
         offset = avio_skip(s->pb, -DSS_AUDIO_BLOCK_HEADER_SIZE);
     } else {
         ctx->counter = DSS_BLOCK_SIZE - offset;
         offset = avio_skip(s->pb, offset - DSS_AUDIO_BLOCK_HEADER_SIZE);
     }
     ctx->dss_sp_swap_byte = -1;
     return 0;
 }
 
 

 AVInputFormat ff_dss_demuxer = {
     .name           = "dss",
     .long_name      = NULL_IF_CONFIG_SMALL("Digital Speech Standard (DSS)"),
     .priv_data_size = sizeof(DSSDemuxContext),
     .read_probe     = dss_probe,
     .read_header    = dss_read_header,
     .read_packet    = dss_read_packet,
     .read_close     = dss_read_close,

     .read_seek      = dss_read_seek,

     .extensions     = "dss"
 };