我正在使用 FFmpeg 从音频文件中获取 LUF 值，但得到了大量的输出。我只想要输出底部附近的最终集成阈值 LUF 值，并且使用 grep 和 regex 取得了一些成功，但我想知道是否有更好的方法只使用 FFmpeg？
这是我使用的命令：
ffmpeg -i test.mp4 -hide_banner -filter_complex ebur128 -f null -
输出为：
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.20.100
Duration: 00:00:05.02, start: 0.000000, bitrate: 780 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 644 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
Metadata:
handler_name : ISO Media file produced by Google Inc.
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 127 kb/s (default)
Metadata:
handler_name : ISO Media file produced by Google Inc.
[Parsed_ebur128_0 @ 0x7feb18604000] Summary:
Integrated loudness:
I: -70.0 LUFS
Threshold: 0.0 LUFS
Loudness range:
LRA: 0.0 LU
Threshold: 0.0 LUFS
LRA low: 0.0 LUFS
LRA high: 0.0 LUFS
Stream mapping:
Stream #0:1 (aac) -> ebur128 (graph 0)
ebur128 (graph 0) -> Stream #0:0 (pcm_s16le)
Stream #0:0 -> #0:1 (h264 (native) -> wrapped_avframe (native))
Press [q] to stop, [?] for help
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 0.0999792 M:-120.7 S:-120.7 I: -70.0 LUFS LRA: 0.0 LU
Output #0, null, to 'pipe:':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.12.100
Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s (default)
Metadata:
encoder : Lavc58.18.100 pcm_s16le
Stream #0:1(und): Video: wrapped_avframe, yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 29.97 fps, 29.97 tbn, 29.97 tbc (default)
Metadata:
handler_name : ISO Media file produced by Google Inc.
encoder : Lavc58.18.100 wrapped_avframe
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 0.199979 M:-120.7 S:-120.7 I: -70.0 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 0.299979 M:-120.7 S:-120.7 I: -70.0 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 0.399979 M: -27.5 S:-120.7 I: -27.5 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 0.499979 M: -27.9 S:-120.7 I: -27.7 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 0.599979 M: -31.9 S:-120.7 I: -28.7 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 0.699979 M: -34.8 S:-120.7 I: -29.6 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 0.799979 M: -38.1 S:-120.7 I: -30.4 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 0.899979 M: -46.6 S:-120.7 I: -30.4 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 0.999979 M: -49.5 S:-120.7 I: -30.4 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 1.09998 M: -57.2 S:-120.7 I: -30.4 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 1.19998 M: -58.1 S:-120.7 I: -30.4 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 1.29998 M: -58.6 S:-120.7 I: -30.4 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 1.39998 M: -58.8 S:-120.7 I: -30.4 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 1.49998 M: -58.7 S:-120.7 I: -30.4 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 1.59998 M: -51.9 S:-120.7 I: -30.4 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 1.69998 M: -33.7 S:-120.7 I: -30.8 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 1.79998 M: -26.0 S:-120.7 I: -29.7 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 1.89998 M: -22.4 S:-120.7 I: -27.8 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 1.99998 M: -22.0 S:-120.7 I: -26.6 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 2.09998 M: -21.1 S:-120.7 I: -25.7 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 2.19998 M: -21.9 S:-120.7 I: -24.8 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 2.29998 M: -24.5 S:-120.7 I: -24.7 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 2.39998 M: -23.4 S:-120.7 I: -24.6 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 2.49998 M: -22.8 S:-120.7 I: -24.4 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 2.59998 M: -21.5 S:-120.7 I: -24.2 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 2.69998 M: -20.0 S:-120.7 I: -23.7 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 2.79998 M: -19.3 S:-120.7 I: -23.3 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 2.89998 M: -20.2 S:-120.7 I: -23.0 LUFS LRA: 0.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 2.99998 M: -21.6 S: -24.8 I: -22.7 LUFS LRA: 20.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 3.09998 M: -24.3 S: -24.8 I: -22.8 LUFS LRA: 20.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 3.19998 M: -32.7 S: -25.0 I: -23.2 LUFS LRA: 20.1 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 3.29998 M: -28.6 S: -24.8 I: -23.3 LUFS LRA: 20.1 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 3.39998 M: -27.0 S: -24.8 I: -23.4 LUFS LRA: 0.2 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 3.49998 M: -26.3 S: -24.7 I: -23.5 LUFS LRA: 0.3 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 3.59998 M: -24.9 S: -24.5 I: -23.6 LUFS LRA: 0.5 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 3.69998 M: -25.7 S: -24.4 I: -23.7 LUFS LRA: 0.5 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 3.79998 M: -25.5 S: -24.3 I: -23.7 LUFS LRA: 0.7 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 3.89998 M: -25.6 S: -24.3 I: -23.8 LUFS LRA: 0.7 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 3.99998 M: -26.7 S: -24.2 I: -23.8 LUFS LRA: 0.7 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 4.09998 M: -26.9 S: -24.1 I: -23.9 LUFS LRA: 0.8 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 4.19998 M: -28.3 S: -24.1 I: -24.0 LUFS LRA: 0.9 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 4.29998 M: -26.3 S: -23.9 I: -24.1 LUFS LRA: 0.9 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 4.39998 M: -25.8 S: -23.8 I: -24.1 LUFS LRA: 0.9 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 4.49998 M: -26.5 S: -23.8 I: -24.2 LUFS LRA: 1.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 4.59998 M: -27.1 S: -23.8 I: -24.2 LUFS LRA: 1.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 4.69998 M: -30.9 S: -23.9 I: -24.3 LUFS LRA: 1.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 4.79998 M: -39.0 S: -24.2 I: -24.3 LUFS LRA: 1.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 4.89998 M: -51.2 S: -24.7 I: -24.3 LUFS LRA: 1.0 LU
[Parsed_ebur128_0 @ 0x7feb187009c0] t: 4.99998 M: -54.8 S: -24.8 I: -24.3 LUFS LRA: 1.0 LU
frame= 150 fps=0.0 q=-0.0 Lsize=N/A time=00:00:05.01 bitrate=N/A speed=17.5x
video:79kB audio:940kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
[Parsed_ebur128_0 @ 0x7feb187009c0] Summary:
Integrated loudness:
I: -24.3 LUFS
Threshold: -35.6 LUFS
Loudness range:
LRA: 1.0 LU
Threshold: -44.4 LUFS
LRA low: -24.9 LUFS
LRA high: -23.8 LUFS
我想让-24.3LUFS 数值接近底部。我尝试过：
ffmpeg -i test.mp4 -hide_banner -filter_complex ebur128 -f null - 2<&1 | grep -E 'I:.+ LUFS$' | tail -1 | grep -E '\-[0-9\.]+'
取得了一些成功，但我正在寻找更有效的方法来做到这一点。
答案1
你可以使用awk：
ffmpeg -i input -af ebur128=framelog=verbose -f null - 2>&1 | awk '/I:/{print $2}'
请注意，具有讽刺意味的是，添加后framelog=verbose，输出比默认的更简洁。
如果你更喜欢使用 JSON，你可以使用劳德诺尔过滤器改为使用print_format=json选项。请参阅loudnorm.rb举个例子。
答案2
过滤最后 12 行（包含来自的 JSON 日志loudnorm），您可以使用jq以一种比较理智的方式解析该值：
ffmpeg -hide_banner -f lavfi -i sine=duration=5 \
-filter:a loudnorm=print_format=json -f null /dev/null 2>&1 \
| tail -n 12 \
| jq '.["input_i"]|tonumber'
仅返回-21.75，没有其他内容。