记录的 FLV 的 FPS 从 60 更改为 62.5 - 严重问题 #Bug

[abrar71]

流式传输 60 FPS 的示例视频文件会将其录制文件的 FPS 更改为 62.5 FPS
OBS 或 WireCast 流媒体软件也存在同样的问题
我在下面附上了 lal 录音文件的输入和输出. 我认为这是一个严重的问题

ffmpeg -i /home/abr/frame_counter_4k_60fps.flv -c copy -f flv rtmp://127.0.0.1:1935/app/frame_counter_stream

Input file:

$ ffmpeg -i frame_counter_4k_60fps.flv
Input #0, flv, from 'frame_counter_4k_60fps.flv':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf59.16.100
  Duration: 00:01:00.04, start: 0.019000, bitrate: 658 kb/s
  Stream #0:0: Video: h264, yuv420p(progressive), 3840x2160 [SAR 1:1 DAR 16:9], 640 kb/s, 60 fps, 60 tbr, 1k tbn
  Stream #0:1: Audio: aac, 48000 Hz, stereo, fltp, 2 kb/s

Recorded file:

$ ffmpeg -i lal_record/flv/frame_counter_stream-1657775570.flv
Input #0, flv, from 'frame_counter_stream-1657775570.flv':
  Duration: 00:00:59.98, start: 0.000000, bitrate: 659 kb/s
  Stream #0:0: Data: none
  Stream #0:1: Video: h264, yuv420p(progressive), 3840x2160 [SAR 1:1 DAR 16:9], 62.50 fps, 60 tbr, 1k tbn
  Stream #0:2: Audio: aac, 48000 Hz, stereo, fltp

English:
Streaming a sample video file at 60 FPS changes the FPS of the recorded file to 62.5 FPS.
The same problem is with OBS or WireCast streaming software.
I have attached the input and output from lal recording files below
This is a critical problem

input_frame_counter_4k_60fps.zip
output_lal_recorded_file.zip
another_sample_file.mp4

#Bug

[abrar71]

Whatever input FPS is provided, the recorded file's FPS is always wrong.
I think the problem might be in packaging RTMP to FLV tags

[q191201771]

简单来说，这是由于ffmpeg推流时，会把原始flv中metadata中的duration字段去除，而lalserver录制的flv，metadata完全使用rtmp的metadata导致的。

现阶段，你可以使用lal中app/demo/pushrtmp替代ffmpeg推流，来解决这个问题。

请问为什么这是一个critical problem？
其他流媒体服务器现象如何？你有空测试并反馈给我吗？

我好评估处理的优先级。

[abrar71]

经过数小时的研究，我认为我们需要在 lal 的 PackHttpflvTag() 函数中使用 https://github.com/gwuhaolin/livego/blob/master/protocol/amf/metadata.go#L31 中的 MetaDataReform() 函数. 像这样：

func PackHttpflvTag(t uint8, timestamp uint32, in []byte) []byte {

	if t == TagTypeMetadata {
		in, _ = amf.MetaDataReform(in, amf.DEL)
	}

	out := make([]byte, TagHeaderSize+len(in)+PrevTagSizeFieldSize)

我已经对此进行了测试，它解决了问题。

[q191201771]

Fixed, try again.

[abrar71]

This resolves the issue, Thank you! I'll test a bit more and then close the issue.

[q191201771]

This resolves the issue, Thank you! I'll test a bit more and then close the issue.

Nice to hear that.
I've modified it a little bit just a moment ago, you shall test the freshest code.