/*
  * WAV muxer
  * Copyright (c) 2001, 2002 Fabrice Bellard
  *

  * Sony Wave64 muxer
  * Copyright (c) 2012 Paul B Mahol
  *

  * WAV muxer RF64 support
  * Copyright (c) 2013 Daniel Verkamp <daniel@drv.nu>
  *

  * EBU Tech 3285 - Supplement 3 - Peak Envelope Chunk encoder
  * Copyright (c) 2014 Georg Lippitsch <georg.lippitsch@gmx.at>
  *

  * 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 <stdint.h>
 #include <string.h>
 

 #include "libavutil/avstring.h"

 #include "libavutil/dict.h"
 #include "libavutil/common.h"

 #include "libavutil/intreadwrite.h"

 #include "libavutil/mathematics.h"
 #include "libavutil/opt.h"

 #include "libavutil/time.h"

 #include "libavutil/time_internal.h"

 
 #include "avformat.h"
 #include "avio.h"
 #include "avio_internal.h"
 #include "internal.h"
 #include "riff.h"
 

 #define RF64_AUTO   (-1)
 #define RF64_NEVER  0
 #define RF64_ALWAYS 1
 

 #define PEAK_BUFFER_SIZE   1024
 
 typedef enum {
     PEAK_OFF = 0,
     PEAK_ON,
     PEAK_ONLY
 } PeakType;
 
 typedef enum {
     PEAK_FORMAT_UINT8 = 1,
     PEAK_FORMAT_UINT16
 } PeakFormat;
 

 typedef struct WAVMuxContext {
     const AVClass *class;
     int64_t data;

     int64_t fact_pos;

     int64_t ds64;

     int64_t minpts;
     int64_t maxpts;

     int16_t *peak_maxpos, *peak_maxneg;
     uint32_t peak_num_frames;
     uint32_t peak_outbuf_size;
     uint32_t peak_outbuf_bytes;
     uint32_t peak_pos_pop;
     uint16_t peak_pop;
     uint8_t *peak_output;

     int last_duration;
     int write_bext;

     int write_peak;

     int rf64;

     int peak_block_size;
     PeakFormat peak_format;
     int peak_block_pos;
     int peak_ppv;
     int peak_bps;

 } WAVMuxContext;
 

 #if CONFIG_WAV_MUXER

 static inline void bwf_write_bext_string(AVFormatContext *s, const char *key, int maxlen)
 {
     AVDictionaryEntry *tag;
     int len = 0;
 
     if (tag = av_dict_get(s->metadata, key, NULL, 0)) {
         len = strlen(tag->value);
         len = FFMIN(len, maxlen);
         avio_write(s->pb, tag->value, len);
     }
 
     ffio_fill(s->pb, 0, maxlen - len);
 }
 
 static void bwf_write_bext_chunk(AVFormatContext *s)
 {
     AVDictionaryEntry *tmp_tag;
     uint64_t time_reference = 0;
     int64_t bext = ff_start_tag(s->pb, "bext");
 
     bwf_write_bext_string(s, "description", 256);
     bwf_write_bext_string(s, "originator", 32);
     bwf_write_bext_string(s, "originator_reference", 32);
     bwf_write_bext_string(s, "origination_date", 10);
     bwf_write_bext_string(s, "origination_time", 8);
 
     if (tmp_tag = av_dict_get(s->metadata, "time_reference", NULL, 0))
         time_reference = strtoll(tmp_tag->value, NULL, 10);
     avio_wl64(s->pb, time_reference);
     avio_wl16(s->pb, 1);  // set version to 1
 
     if (tmp_tag = av_dict_get(s->metadata, "umid", NULL, 0)) {
         unsigned char umidpart_str[17] = {0};
         int i;
         uint64_t umidpart;
         int len = strlen(tmp_tag->value+2);
 
         for (i = 0; i < len/16; i++) {
             memcpy(umidpart_str, tmp_tag->value + 2 + (i*16), 16);
             umidpart = strtoll(umidpart_str, NULL, 16);
             avio_wb64(s->pb, umidpart);
         }
         ffio_fill(s->pb, 0, 64 - i*8);
     } else
         ffio_fill(s->pb, 0, 64); // zero UMID
 
     ffio_fill(s->pb, 0, 190); // Reserved
 
     if (tmp_tag = av_dict_get(s->metadata, "coding_history", NULL, 0))
         avio_put_str(s->pb, tmp_tag->value);
 
     ff_end_tag(s->pb, bext);
 }
 

 static av_cold void peak_free_buffers(AVFormatContext *s)
 {
     WAVMuxContext *wav = s->priv_data;
 
     av_freep(&wav->peak_maxpos);
     av_freep(&wav->peak_maxneg);
     av_freep(&wav->peak_output);
 }
 
 static av_cold int peak_init_writer(AVFormatContext *s)
 {
     WAVMuxContext *wav = s->priv_data;
     AVCodecContext *enc = s->streams[0]->codec;
 
     if (enc->codec_id != AV_CODEC_ID_PCM_S8 &&
         enc->codec_id != AV_CODEC_ID_PCM_S16LE &&
         enc->codec_id != AV_CODEC_ID_PCM_U8 &&
         enc->codec_id != AV_CODEC_ID_PCM_U16LE) {
         av_log(s, AV_LOG_ERROR, "%s codec not supported for Peak Chunk\n",
                s->streams[0]->codec->codec ? s->streams[0]->codec->codec->name : "NONE");
         return -1;
     }
 
     wav->peak_bps = av_get_bits_per_sample(enc->codec_id) / 8;
 
     if (wav->peak_bps == 1 && wav->peak_format == PEAK_FORMAT_UINT16) {
         av_log(s, AV_LOG_ERROR,
                "Writing 16 bit peak for 8 bit audio does not make sense\n");

         return AVERROR(EINVAL);

     }
 

     wav->peak_maxpos = av_mallocz_array(enc->channels, sizeof(*wav->peak_maxpos));
     wav->peak_maxneg = av_mallocz_array(enc->channels, sizeof(*wav->peak_maxneg));

     wav->peak_output = av_malloc(PEAK_BUFFER_SIZE);

     if (!wav->peak_maxpos || !wav->peak_maxneg || !wav->peak_output)

         goto nomem;
 
     wav->peak_outbuf_size = PEAK_BUFFER_SIZE;
 
     return 0;
 
 nomem:
     av_log(s, AV_LOG_ERROR, "Out of memory\n");
     peak_free_buffers(s);
     return AVERROR(ENOMEM);
 }
 
 static void peak_write_frame(AVFormatContext *s)
 {
     WAVMuxContext *wav = s->priv_data;
     AVCodecContext *enc = s->streams[0]->codec;
     int peak_of_peaks;
     int c;
 
     if (!wav->peak_output)
         return;
 
     for (c = 0; c < enc->channels; c++) {
         wav->peak_maxneg[c] = -wav->peak_maxneg[c];
 
         if (wav->peak_bps == 2 && wav->peak_format == PEAK_FORMAT_UINT8) {
             wav->peak_maxpos[c] = wav->peak_maxpos[c] / 256;
             wav->peak_maxneg[c] = wav->peak_maxneg[c] / 256;
         }
 
         if (wav->peak_ppv == 1)
             wav->peak_maxpos[c] =
                 FFMAX(wav->peak_maxpos[c], wav->peak_maxneg[c]);
 
         peak_of_peaks = FFMAX3(wav->peak_maxpos[c], wav->peak_maxneg[c],
                                wav->peak_pop);
         if (peak_of_peaks > wav->peak_pop)
             wav->peak_pos_pop = wav->peak_num_frames;
         wav->peak_pop = peak_of_peaks;
 
         if (wav->peak_outbuf_size - wav->peak_outbuf_bytes <
             wav->peak_format * wav->peak_ppv) {
             wav->peak_outbuf_size += PEAK_BUFFER_SIZE;
             wav->peak_output = av_realloc(wav->peak_output,
                                           wav->peak_outbuf_size);
             if (!wav->peak_output) {
                 av_log(s, AV_LOG_ERROR, "No memory for peak data\n");
                 return;
             }
         }
 
         if (wav->peak_format == PEAK_FORMAT_UINT8) {
             wav->peak_output[wav->peak_outbuf_bytes++] =
                 wav->peak_maxpos[c];
             if (wav->peak_ppv == 2) {
                 wav->peak_output[wav->peak_outbuf_bytes++] =
                     wav->peak_maxneg[c];
             }
         } else {
             AV_WL16(wav->peak_output + wav->peak_outbuf_bytes,
                     wav->peak_maxpos[c]);
             wav->peak_outbuf_bytes += 2;
             if (wav->peak_ppv == 2) {
                 AV_WL16(wav->peak_output + wav->peak_outbuf_bytes,
                         wav->peak_maxneg[c]);
                 wav->peak_outbuf_bytes += 2;
             }
         }
         wav->peak_maxpos[c] = 0;
         wav->peak_maxneg[c] = 0;
     }
     wav->peak_num_frames++;
 }
 

 static int peak_write_chunk(AVFormatContext *s)

 {
     WAVMuxContext *wav = s->priv_data;
     AVIOContext *pb = s->pb;
     AVCodecContext *enc = s->streams[0]->codec;
     int64_t peak = ff_start_tag(s->pb, "levl");
     int64_t now0;
     time_t now_secs;
     char timestamp[28];
 
     /* Peak frame of incomplete block at end */
     if (wav->peak_block_pos)
         peak_write_frame(s);
 

     memset(timestamp, 0, sizeof(timestamp));

     if (!(s->flags & AVFMT_FLAG_BITEXACT)) {

         struct tm tmpbuf;

         av_log(s, AV_LOG_INFO, "Writing local time and date to Peak Envelope Chunk\n");
         now0 = av_gettime();
         now_secs = now0 / 1000000;

         if (strftime(timestamp, sizeof(timestamp), "%Y:%m:%d:%H:%M:%S:", localtime_r(&now_secs, &tmpbuf))) {
             av_strlcatf(timestamp, sizeof(timestamp), "%03d", (int)((now0 / 1000) % 1000));
         } else {
             av_log(s, AV_LOG_ERROR, "Failed to write timestamp\n");
             return -1;
         }

     }
 
     avio_wl32(pb, 1);                           /* version */
     avio_wl32(pb, wav->peak_format);            /* 8 or 16 bit */
     avio_wl32(pb, wav->peak_ppv);               /* positive and negative */
     avio_wl32(pb, wav->peak_block_size);        /* frames per value */
     avio_wl32(pb, enc->channels);               /* number of channels */
     avio_wl32(pb, wav->peak_num_frames);        /* number of peak frames */
     avio_wl32(pb, wav->peak_pos_pop);           /* audio sample frame index */
     avio_wl32(pb, 128);                         /* equal to size of header */
     avio_write(pb, timestamp, 28);              /* ASCII time stamp */
     ffio_fill(pb, 0, 60);
 
     avio_write(pb, wav->peak_output, wav->peak_outbuf_bytes);
 
     ff_end_tag(pb, peak);
 
     if (!wav->data)
         wav->data = peak;

 
     return 0;

 }
 

 static int wav_write_header(AVFormatContext *s)
 {
     WAVMuxContext *wav = s->priv_data;
     AVIOContext *pb = s->pb;

     int64_t fmt;

     if (s->nb_streams != 1) {
         av_log(s, AV_LOG_ERROR, "WAVE files have exactly one stream\n");
         return AVERROR(EINVAL);
     }
 

     if (wav->rf64 == RF64_ALWAYS) {
         ffio_wfourcc(pb, "RF64");
         avio_wl32(pb, -1); /* RF64 chunk size: use size in ds64 */
     } else {

         ffio_wfourcc(pb, "RIFF");

         avio_wl32(pb, -1); /* file length */

     }
 

     ffio_wfourcc(pb, "WAVE");
 

     if (wav->rf64 != RF64_NEVER) {
         /* write empty ds64 chunk or JUNK chunk to reserve space for ds64 */
         ffio_wfourcc(pb, wav->rf64 == RF64_ALWAYS ? "ds64" : "JUNK");
         avio_wl32(pb, 28); /* chunk size */
         wav->ds64 = avio_tell(pb);
         ffio_fill(pb, 0, 28);
     }
 

     if (wav->write_peak != 2) {

         /* format header */
         fmt = ff_start_tag(pb, "fmt ");
         if (ff_put_wav_header(pb, s->streams[0]->codec, 0) < 0) {
             const AVCodecDescriptor *desc = avcodec_descriptor_get(s->streams[0]->codec->codec_id);
             av_log(s, AV_LOG_ERROR, "%s codec not supported in WAVE format\n",
                    desc ? desc->name : "unknown");
             return AVERROR(ENOSYS);
         }
         ff_end_tag(pb, fmt);

     }

 
     if (s->streams[0]->codec->codec_tag != 0x01 /* hence for all other than PCM */
         && s->pb->seekable) {

         wav->fact_pos = ff_start_tag(pb, "fact");

         avio_wl32(pb, 0);

         ff_end_tag(pb, wav->fact_pos);

     }
 
     if (wav->write_bext)
         bwf_write_bext_chunk(s);
 

     if (wav->write_peak) {
         int ret;
         if ((ret = peak_init_writer(s)) < 0)
             return ret;
     }
 

     avpriv_set_pts_info(s->streams[0], 64, 1, s->streams[0]->codec->sample_rate);
     wav->maxpts = wav->last_duration = 0;
     wav->minpts = INT64_MAX;
 

     if (wav->write_peak != 2) {

         /* info header */
         ff_riff_write_info(s);

         /* data header */
         wav->data = ff_start_tag(pb, "data");

     }

 
     avio_flush(pb);
 
     return 0;
 }
 
 static int wav_write_packet(AVFormatContext *s, AVPacket *pkt)
 {
     AVIOContext *pb  = s->pb;
     WAVMuxContext    *wav = s->priv_data;

 
     if (wav->write_peak != 2)

         avio_write(pb, pkt->data, pkt->size);

 
     if (wav->write_peak) {
         int c = 0;
         int i;
         for (i = 0; i < pkt->size; i += wav->peak_bps) {
             if (wav->peak_bps == 1) {
                 wav->peak_maxpos[c] = FFMAX(wav->peak_maxpos[c], *(int8_t*)(pkt->data + i));
                 wav->peak_maxneg[c] = FFMIN(wav->peak_maxneg[c], *(int8_t*)(pkt->data + i));
             } else {
                 wav->peak_maxpos[c] = FFMAX(wav->peak_maxpos[c], (int16_t)AV_RL16(pkt->data + i));
                 wav->peak_maxneg[c] = FFMIN(wav->peak_maxneg[c], (int16_t)AV_RL16(pkt->data + i));
             }
             if (++c == s->streams[0]->codec->channels) {
                 c = 0;
                 if (++wav->peak_block_pos == wav->peak_block_size) {
                     peak_write_frame(s);
                     wav->peak_block_pos = 0;
                 }
             }
         }
     }
 

     if(pkt->pts != AV_NOPTS_VALUE) {
         wav->minpts        = FFMIN(wav->minpts, pkt->pts);
         wav->maxpts        = FFMAX(wav->maxpts, pkt->pts);
         wav->last_duration = pkt->duration;
     } else
         av_log(s, AV_LOG_ERROR, "wav_write_packet: NOPTS\n");
     return 0;
 }
 
 static int wav_write_trailer(AVFormatContext *s)
 {
     AVIOContext *pb  = s->pb;
     WAVMuxContext    *wav = s->priv_data;

     int64_t file_size, data_size;
     int64_t number_of_samples = 0;
     int rf64 = 0;

     int ret = 0;

 
     avio_flush(pb);
 
     if (s->pb->seekable) {

         if (wav->write_peak != 2) {
             ff_end_tag(pb, wav->data);
             avio_flush(pb);
         }
 
         if (wav->write_peak && wav->peak_output) {

             ret = peak_write_chunk(s);

             avio_flush(pb);
         }
 

         /* update file size */
         file_size = avio_tell(pb);

         data_size = file_size - wav->data;
         if (wav->rf64 == RF64_ALWAYS || (wav->rf64 == RF64_AUTO && file_size - 8 > UINT32_MAX)) {
             rf64 = 1;
         } else {

             avio_seek(pb, 4, SEEK_SET);
             avio_wl32(pb, (uint32_t)(file_size - 8));
             avio_seek(pb, file_size, SEEK_SET);

             avio_flush(pb);

         }

         number_of_samples = av_rescale(wav->maxpts - wav->minpts + wav->last_duration,
                                        s->streams[0]->codec->sample_rate * (int64_t)s->streams[0]->time_base.num,
                                        s->streams[0]->time_base.den);

 
         if(s->streams[0]->codec->codec_tag != 0x01) {
             /* Update num_samps in fact chunk */

             avio_seek(pb, wav->fact_pos, SEEK_SET);

             if (rf64 || (wav->rf64 == RF64_AUTO && number_of_samples > UINT32_MAX)) {
                 rf64 = 1;
                 avio_wl32(pb, -1);
             } else {

                 avio_wl32(pb, number_of_samples);
                 avio_seek(pb, file_size, SEEK_SET);
                 avio_flush(pb);

             }
         }
 
         if (rf64) {
             /* overwrite RIFF with RF64 */
             avio_seek(pb, 0, SEEK_SET);
             ffio_wfourcc(pb, "RF64");
             avio_wl32(pb, -1);
 
             /* write ds64 chunk (overwrite JUNK if rf64 == RF64_AUTO) */
             avio_seek(pb, wav->ds64 - 8, SEEK_SET);
             ffio_wfourcc(pb, "ds64");
             avio_wl32(pb, 28);                  /* ds64 chunk size */
             avio_wl64(pb, file_size - 8);       /* RF64 chunk size */
             avio_wl64(pb, data_size);           /* data chunk size */
             avio_wl64(pb, number_of_samples);   /* fact chunk number of samples */
             avio_wl32(pb, 0);                   /* number of table entries for non-'data' chunks */
 
             /* write -1 in data chunk size */
             avio_seek(pb, wav->data - 4, SEEK_SET);
             avio_wl32(pb, -1);
 
             avio_seek(pb, file_size, SEEK_SET);
             avio_flush(pb);

         }
     }

 
     if (wav->write_peak)
         peak_free_buffers(s);
 

     return ret;

 }
 
 #define OFFSET(x) offsetof(WAVMuxContext, x)
 #define ENC AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {
     { "write_bext", "Write BEXT chunk.", OFFSET(write_bext), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, ENC },

     { "write_peak", "Write Peak Envelope chunk.",            OFFSET(write_peak), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 2, ENC, "peak" },
     { "off",        "Do not write peak chunk.",              0,                  AV_OPT_TYPE_CONST, { .i64 = PEAK_OFF  }, 0, 0, ENC, "peak" },
     { "on",         "Append peak chunk after wav data.",     0,                  AV_OPT_TYPE_CONST, { .i64 = PEAK_ON   }, 0, 0, ENC, "peak" },
     { "only",       "Write only peak chunk, omit wav data.", 0,                  AV_OPT_TYPE_CONST, { .i64 = PEAK_ONLY }, 0, 0, ENC, "peak" },

     { "rf64",       "Use RF64 header rather than RIFF for large files.",    OFFSET(rf64), AV_OPT_TYPE_INT,   { .i64 = RF64_NEVER  },-1, 1, ENC, "rf64" },
     { "auto",       "Write RF64 header if file grows large enough.",        0,            AV_OPT_TYPE_CONST, { .i64 = RF64_AUTO   }, 0, 0, ENC, "rf64" },
     { "always",     "Always write RF64 header regardless of file size.",    0,            AV_OPT_TYPE_CONST, { .i64 = RF64_ALWAYS }, 0, 0, ENC, "rf64" },
     { "never",      "Never write RF64 header regardless of file size.",     0,            AV_OPT_TYPE_CONST, { .i64 = RF64_NEVER  }, 0, 0, ENC, "rf64" },

     { "peak_block_size", "Number of audio samples used to generate each peak frame.",   OFFSET(peak_block_size), AV_OPT_TYPE_INT, { .i64 = 256 }, 0, 65536, ENC },
     { "peak_format",     "The format of the peak envelope data (1: uint8, 2: uint16).", OFFSET(peak_format), AV_OPT_TYPE_INT,     { .i64 = PEAK_FORMAT_UINT16 }, PEAK_FORMAT_UINT8, PEAK_FORMAT_UINT16, ENC },
     { "peak_ppv",        "Number of peak points per peak value (1 or 2).",              OFFSET(peak_ppv), AV_OPT_TYPE_INT, { .i64 = 2 }, 1, 2, ENC },

     { NULL },
 };
 
 static const AVClass wav_muxer_class = {
     .class_name = "WAV muxer",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
 AVOutputFormat ff_wav_muxer = {
     .name              = "wav",
     .long_name         = NULL_IF_CONFIG_SMALL("WAV / WAVE (Waveform Audio)"),
     .mime_type         = "audio/x-wav",
     .extensions        = "wav",
     .priv_data_size    = sizeof(WAVMuxContext),
     .audio_codec       = AV_CODEC_ID_PCM_S16LE,
     .video_codec       = AV_CODEC_ID_NONE,
     .write_header      = wav_write_header,
     .write_packet      = wav_write_packet,
     .write_trailer     = wav_write_trailer,
     .flags             = AVFMT_TS_NONSTRICT,
     .codec_tag         = (const AVCodecTag* const []){ ff_codec_wav_tags, 0 },
     .priv_class        = &wav_muxer_class,
 };

 #endif /* CONFIG_WAV_MUXER */
 
 #if CONFIG_W64_MUXER
 #include "w64.h"
 
 static void start_guid(AVIOContext *pb, const uint8_t *guid, int64_t *pos)
 {
     *pos = avio_tell(pb);
 
     avio_write(pb, guid, 16);
     avio_wl64(pb, INT64_MAX);
 }
 
 static void end_guid(AVIOContext *pb, int64_t start)
 {
     int64_t end, pos = avio_tell(pb);
 
     end = FFALIGN(pos, 8);
     ffio_fill(pb, 0, end - pos);
     avio_seek(pb, start + 16, SEEK_SET);
     avio_wl64(pb, end - start);
     avio_seek(pb, end, SEEK_SET);
 }
 
 static int w64_write_header(AVFormatContext *s)
 {
     WAVMuxContext *wav = s->priv_data;
     AVIOContext *pb = s->pb;
     int64_t start;
     int ret;
 
     avio_write(pb, ff_w64_guid_riff, sizeof(ff_w64_guid_riff));
     avio_wl64(pb, -1);
     avio_write(pb, ff_w64_guid_wave, sizeof(ff_w64_guid_wave));
     start_guid(pb, ff_w64_guid_fmt, &start);

     if ((ret = ff_put_wav_header(pb, s->streams[0]->codec, 0)) < 0) {

         av_log(s, AV_LOG_ERROR, "%s codec not supported\n",
                s->streams[0]->codec->codec ? s->streams[0]->codec->codec->name : "NONE");
         return ret;
     }
     end_guid(pb, start);

 
     if (s->streams[0]->codec->codec_tag != 0x01 /* hence for all other than PCM */
         && s->pb->seekable) {
         start_guid(pb, ff_w64_guid_fact, &wav->fact_pos);
         avio_wl64(pb, 0);
         end_guid(pb, wav->fact_pos);
     }
 

     start_guid(pb, ff_w64_guid_data, &wav->data);
 
     return 0;
 }
 
 static int w64_write_trailer(AVFormatContext *s)
 {
     AVIOContext    *pb = s->pb;
     WAVMuxContext *wav = s->priv_data;
     int64_t file_size;
 
     if (pb->seekable) {
         end_guid(pb, wav->data);
 
         file_size = avio_tell(pb);
         avio_seek(pb, 16, SEEK_SET);
         avio_wl64(pb, file_size);
 

         if (s->streams[0]->codec->codec_tag != 0x01) {
             int64_t number_of_samples;
 
             number_of_samples = av_rescale(wav->maxpts - wav->minpts + wav->last_duration,
                                            s->streams[0]->codec->sample_rate * (int64_t)s->streams[0]->time_base.num,
                                            s->streams[0]->time_base.den);
             avio_seek(pb, wav->fact_pos + 24, SEEK_SET);
             avio_wl64(pb, number_of_samples);
         }
 
         avio_seek(pb, file_size, SEEK_SET);

         avio_flush(pb);
     }
 
     return 0;
 }
 
 AVOutputFormat ff_w64_muxer = {
     .name              = "w64",
     .long_name         = NULL_IF_CONFIG_SMALL("Sony Wave64"),
     .extensions        = "w64",
     .priv_data_size    = sizeof(WAVMuxContext),
     .audio_codec       = AV_CODEC_ID_PCM_S16LE,
     .video_codec       = AV_CODEC_ID_NONE,
     .write_header      = w64_write_header,
     .write_packet      = wav_write_packet,
     .write_trailer     = w64_write_trailer,
     .flags             = AVFMT_TS_NONSTRICT,
     .codec_tag         = (const AVCodecTag* const []){ ff_codec_wav_tags, 0 },
 };
 #endif /* CONFIG_W64_MUXER */