ffmpeg音频pcm重采样48000到44100

最新推荐文章于 2025-06-14 17:50:32 发布

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最新推荐文章于 2025-06-14 17:50:32 发布 · 7.2k 阅读

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#ffmpeg #pcm #重采样 #48000 #swr_convert

为了符合FLV封装标准，使用ffmpeg将48000采样率的PCM重采样为44100。在重采样过程中，原始PCM数据为AV_SAMPLE_FMT_S16，经过ffmpeg的重采样后，数据仍保持16位交错存储。文章提供了一段使用ffmpeg进行重采样的代码示例，以及PCM文件的下载链接和编译命令。

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ffmpeg音频pcm重采样48000到44100

为何要重采样

一些工作的需要，需要保存成FLV文件，而在保存的过程中，48000的采样率并不符合用FLV的封装标准（最高44100），所以在这里通过调用ffmpeg来重采样pcm，并保存文件。

代码

ffmpeg版本3.4.2

/*
 * Copyright (c) 2012 Stefano Sabatini
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

/**
 * @example resampling_audio.c
 * libswresample API use example.
 */

extern "C"
{
   
   
#include <stdio.h>
#include <libavutil/opt.h>
#include <libavutil/channel_layout.h>
#include <libavutil/samplefmt.h>
#include <libswresample/swresample.h>

static int get_format_from_sample_fmt(const char **fmt,
                                      enum AVSampleFormat sample_fmt)
{
   
   
    int i;
    struct sample_fmt_entry {
   
   
        enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le;
    } sample_fmt_entries[] = {
   
   
        {
   
    AV_SAMPLE_FMT_U8,  "u8",    "u8"    },
        {
   
    AV_SAMPLE_FMT_S16, "s16be", "s16le" },
        {
   
    AV_SAMPLE_FMT_S32, "s32be", "s32le" },
        {
   
    AV_SAMPLE_FMT_FLT, "f32be", "f32le" },
        {
   
    AV_SAMPLE_FMT_DBL, "f64be", "f64le" },
    };
    *fmt = NULL;

    for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) {
   
   
        struct sample_fmt_entry *entry = &sample_fmt_entries[i];
        if (sample_fmt == entry->sample_fmt) {
   
   
            *fmt = AV_NE(entry->fmt_be, entry->fmt_le);
            return 0;
        }
    }