我正在使用通过Homebrew安装的libav 9.6。
$ avprobe -version
avprobe version 9.6, Copyright (c) 2007-2013 the Libav developers
built on Jun 8 2013 02:44:19 with Apple LLVM version 4.2 (clang-425.0.24) (based on LLVM 3.2svn)
avprobe 9.6
libavutil 52. 3. 0 / 52. 3. 0
libavcodec 54. 35. 0 / 54. 35. 0
libavformat 54. 20. 3 / 54. 20. 3
libavdevice 53. 2. 0 / 53. 2. 0
libavfilter 3. 3. 0 / 3. 3. 0
libavresample 1. 0. 1 / 1. 0. 1
libswscale 2. 1. 1 / 2. 1. 1
尽管取样率在命令行输出的标准输出中显示,但-show_format
选项根本不会在音频文件中呈现取样率信息。
这是BASH终端输出:
$ avprobe -v verbose -show_format -of json sample.gsm
avprobe version 9.6, Copyright (c) 2007-2013 the Libav developers
built on Jun 8 2013 02:44:19 with Apple LLVM version 4.2 (clang-425.0.24)
(based on LLVM 3.2svn)
configuration: --prefix=/usr/local/Cellar/libav/9.6 --enable-shared
--enable-pthreads --enable-gpl --enable-version3 --enable-nonfree
--enable-hardcoded-tables --enable-avresample --enable-vda --enable-gnutls
--enable-runtime-cpudetect --disable-indev=jack --cc=cc --host-cflags=
--host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame
--enable-libxvid --enable-avplay
libavutil 52. 3. 0 / 52. 3. 0
libavcodec 54. 35. 0 / 54. 35. 0
libavformat 54. 20. 3 / 54. 20. 3
libavdevice 53. 2. 0 / 53. 2. 0
libavfilter 3. 3. 0 / 3. 3. 0
libavresample 1. 0. 1 / 1. 0. 1
libswscale 2. 1. 1 / 2. 1. 1
[gsm @ 0x7f8012806600] Estimating duration from bitrate, this may be inaccurate
Input #0, gsm, from 'sample.gsm':
Duration: 00:03:52.32, start: 0.000000, bitrate: 13 kb/s
Stream #0.0: Audio: gsm, 8000 Hz, mono, s16, 13 kb/s
{ "format" : {
"filename" : "sample.gsm",
"nb_streams" : 1,
"format_name" : "gsm",
"format_long_name" : "raw GSM",
"start_time" : "0.000000",
"duration" : "232.320000",
"size" : "383328.000000",
"bit_rate" : "13200.000000"
}}
而且这是Python代码示例:
>>> filename = 'sample.gsm'
>>> result = subprocess.check_output(['avprobe', '-show_format', '-of',
'json', filename])
avprobe version 9.6, Copyright (c) 2007-2013 the Libav developers
built on Jun 8 2013 02:44:19 with Apple LLVM version 4.2
(clang-425.0.24) (based on LLVM 3.2svn)
[gsm @ 0x7fe0b1806600] Estimating duration from bitrate, this may be
inaccurate
Input #0, gsm, from 'sample.gsm':
Duration: 00:03:52.32, start: 0.000000, bitrate: 13 kb/s
Stream #0.0: Audio: gsm, 8000 Hz, mono, s16, 13 kb/s
>>> print result
{ "format" : {
"filename" : "sample.gsm",
"nb_streams" : 1,
"format_name" : "gsm",
"format_long_name" : "raw GSM",
"start_time" : "0.000000",
"duration" : "232.320000",
"size" : "383328.000000",
"bit_rate" : "13200.000000"
}}
我知道采样率可能是一个流特定的显示,可以在 -show_format
选项结果中显示。但即使可以在重新编码时使用 -ar
进行设置,也没有其他选项可以检测特定音频流的采样率。
我向 libav 提交了一张工单,但我只是好奇是否有其他方法从 libav 探测工具中提取采样率。非常感谢您的回答。
PS:针对 ffmpeg 的上游项目(ffprobe)来说,这将是相同的问题。
-show_streams
有效 :) - Devy-select_stream a
,得到类似以下的命令:ffprobe -select_streams a -show_streams input.flac
。 - Quar