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ffmpeg-4.2.2/libswresample/soxr_resample.c 4.39 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * audio resampling with soxr
   * Copyright (c) 2012 Rob Sykes <robs@users.sourceforge.net>
   *
   * 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
   */
  
  /**
   * @file
   * audio resampling with soxr
   */
  
  #include "libavutil/log.h"
  #include "swresample_internal.h"
  
  #include <soxr.h>
  
  static struct ResampleContext *create(struct ResampleContext *c, int out_rate, int in_rate, int filter_size, int phase_shift, int linear,
          double cutoff, enum AVSampleFormat format, enum SwrFilterType filter_type, double kaiser_beta, double precision, int cheby, int exact_rational){
      soxr_error_t error;
  
      soxr_datatype_t type =
          format == AV_SAMPLE_FMT_S16P? SOXR_INT16_S :
          format == AV_SAMPLE_FMT_S16 ? SOXR_INT16_I :
          format == AV_SAMPLE_FMT_S32P? SOXR_INT32_S :
          format == AV_SAMPLE_FMT_S32 ? SOXR_INT32_I :
          format == AV_SAMPLE_FMT_FLTP? SOXR_FLOAT32_S :
          format == AV_SAMPLE_FMT_FLT ? SOXR_FLOAT32_I :
          format == AV_SAMPLE_FMT_DBLP? SOXR_FLOAT64_S :
          format == AV_SAMPLE_FMT_DBL ? SOXR_FLOAT64_I : (soxr_datatype_t)-1;
  
      soxr_io_spec_t io_spec = soxr_io_spec(type, type);
  
      soxr_quality_spec_t q_spec = soxr_quality_spec((int)((precision-2)/4), (SOXR_HI_PREC_CLOCK|SOXR_ROLLOFF_NONE)*!!cheby);
      q_spec.precision = precision;
  #if !defined SOXR_VERSION /* Deprecated @ March 2013: */
      q_spec.bw_pc = cutoff? FFMAX(FFMIN(cutoff,.995),.8)*100 : q_spec.bw_pc;
  #else
      q_spec.passband_end = cutoff? FFMAX(FFMIN(cutoff,.995),.8) : q_spec.passband_end;
  #endif
  
      soxr_delete((soxr_t)c);
      c = (struct ResampleContext *)
          soxr_create(in_rate, out_rate, 0, &error, &io_spec, &q_spec, 0);
      if (!c)
          av_log(NULL, AV_LOG_ERROR, "soxr_create: %s\n", error);
      return c;
  }
  
  static void destroy(struct ResampleContext * *c){
      soxr_delete((soxr_t)*c);
      *c = NULL;
  }
  
  static int flush(struct SwrContext *s){
      s->delayed_samples_fixup = soxr_delay((soxr_t)s->resample);
  
      soxr_process((soxr_t)s->resample, NULL, 0, NULL, NULL, 0, NULL);
  
      {
          float f;
          size_t idone, odone;
          soxr_process((soxr_t)s->resample, &f, 0, &idone, &f, 0, &odone);
          s->delayed_samples_fixup -= soxr_delay((soxr_t)s->resample);
      }
  
      return 0;
  }
  
  static int process(
          struct ResampleContext * c, AudioData *dst, int dst_size,
          AudioData *src, int src_size, int *consumed){
      size_t idone, odone;
      soxr_error_t error = soxr_set_error((soxr_t)c, soxr_set_num_channels((soxr_t)c, src->ch_count));
      if (!error)
          error = soxr_process((soxr_t)c, src->ch, (size_t)src_size,
                               &idone, dst->ch, (size_t)dst_size, &odone);
      else
          idone = 0;
  
      *consumed = (int)idone;
      return error? -1 : odone;
  }
  
  static int64_t get_delay(struct SwrContext *s, int64_t base){
      double delayed_samples = soxr_delay((soxr_t)s->resample);
      double delay_s;
  
      if (s->flushed)
          delayed_samples += s->delayed_samples_fixup;
  
      delay_s = delayed_samples / s->out_sample_rate;
  
      return (int64_t)(delay_s * base + .5);
  }
  
  static int invert_initial_buffer(struct ResampleContext *c, AudioData *dst, const AudioData *src,
                                   int in_count, int *out_idx, int *out_sz){
      return 0;
  }
  
  static int64_t get_out_samples(struct SwrContext *s, int in_samples){
      double out_samples = (double)s->out_sample_rate / s->in_sample_rate * in_samples;
      double delayed_samples = soxr_delay((soxr_t)s->resample);
  
      if (s->flushed)
          delayed_samples += s->delayed_samples_fixup;
  
      return (int64_t)(out_samples + delayed_samples + 1 + .5);
  }
  
  struct Resampler const swri_soxr_resampler={
      create, destroy, process, flush, NULL /* set_compensation */, get_delay,
      invert_initial_buffer, get_out_samples
  };