ffmpeg：读取标头管道时出错：0：参数无效

Question

我需要微服务（使用流转换音频），但 ffmpeg 有问题

我的测试 ffmpeg

package codec

import (
    "bytes"
    "os"
    "os/exec"
    "testing"
)

func Test1(t *testing.T) {
    in, err := os.Open("/mp4-mp3/src.m4a")
    if err != nil {
        t.Fatal(err.Error())
    }
    out, err := os.OpenFile("/mp4-mp3/out.mp3", os.O_RDWR|os.O_CREATE, 0666)
    if err != nil {
        t.Fatal(err.Error())
    }
    cmd := exec.Command(
        "ffmpeg",
        "-f", "m4a",
        "-i", "pipe:0",
        "-f", "mp3",
        "pipe:1")

    cmd.Stdin = in
    cmd.Stdout = out
    stderr := &bytes.Buffer{}
    cmd.Stderr = stderr
    if err := cmd.Run(); err != nil {
        t.Logf(stderr.String())
        t.Fatal(err.Error())
    }

}

在出口处，我有错误无效参数 我尝试了不同的选项，但问题没有改变

=== RUN   Test1
    codec_test.go:31: ffmpeg version git-2020-08-31-4a11a6f Copyright (c) 2000-2020 the FFmpeg developers
          built with gcc 10.2.1 (GCC) 20200805
          configuration: hide...
          libavutil      56. 58.100 / 56. 58.100
          libavcodec     58.101.101 / 58.101.101
          libavformat    58. 51.101 / 58. 51.101
          libavdevice    58. 11.101 / 58. 11.101
          libavfilter     7. 87.100 /  7. 87.100
          libswscale      5.  8.100 /  5.  8.100
          libswresample   3.  8.100 /  3.  8.100
          libpostproc    55.  8.100 / 55.  8.100
        [mov,mp4,m4a,3gp,3g2,mj2 @ 0000019ccc3acb40] error reading header
        pipe:0: Invalid argument
    codec_test.go:32: exit status 1
--- FAIL: Test1 (0.07s)
FAIL

Process finished with exit code 1

我决定使用 cmd，但我有新问题 pipe:0: 处理输入时发现无效数据

cat src.m4a | ffmpeg -f m4a -i pipe:0 out.mp3
ffmpeg version git-2020-08-31-4a11a6f Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 10.2.1 (GCC) 20200805
  configuration: hide...
  libavutil      56. 58.100 / 56. 58.100
  libavcodec     58.101.101 / 58.101.101
  libavformat    58. 51.101 / 58. 51.101
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0000019afa98d800] invalid STSD entries 1
[mov,mp4,m4a,3gp,3g2,mj2 @ 0000019afa98d800] error reading header
pipe:0: Invalid data found when processing input

如何正确设置ffmpeg参数以实现流转流？

Answer 1

通常，mp4 无法通过pipe 协议加载。无法顺序读取视频容器。如果mp4 是created with some special flags，则可以缓解这种情况，但这些可能会导致一些其他问题。