YouTube即时串流 [英] Youtube live streaming

问题描述

每个人我使用Logitech C920R实时分发到Youtube.

Everyone I use the Logitech C920R to distribute live to Youtube.

命令如下.

#! / bin / sh
YOUTUBE_URL = "rtmp: //a.rtmp.youtube.com/live2"
KEY = "xxxx-yyyy-zzzz"
v4l2 - ctl --device = / dev / video0 - set - fmt - video = width = 1280, height = 720
ffmpeg - ar 44100 - ac 2 - f alsa - i hw: 1,0 - f v 4 l 2 - codec: v h 264 - framerate 30 - video-- size 1280 x 720 --itsoffset 0.5 \
-i / dev / video0 - copyyinkf - codec: v copy - codec: a aac - ab 128 k - g 10 - strict experimental \
-f flv $ YOUTUBE_URL / $ KEY
1> / dev / null 2> / dev / null &

运行此命令时，收到以下消息.

When I run this command, I get the following message.

[alsa @ 0xbbe770] ALSA buffer xrun.
[video4linux2,v4l2 @ 0xbc92d0] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)
[alsa @ 0xbbe770] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)
[flv @ 0xc3d940] Non-monotonous DTS in output stream 0:0; previous: 500, current: 329; changing to 500. This may result in incorrect timestamps in the output file.
[flv @ 0xc3d940] Non-monotonous DTS in output stream 0:0; previous: 500, current: 361; changing to 500. This may result in incorrect timestamps in the output file.
[flv @ 0xc3d940] Non-monotonous DTS in output stream 0:0; previous: 500, current: 393; changing to 500. This may result in incorrect timestamps in the output file.
[flv @ 0xc3d940] Non-monotonous DTS in output stream 0:0; previous: 500, current: 429; changing to 500. This may result in incorrect timestamps in the output file.
[flv @ 0xc3d940] Non-monotonous DTS in output stream 0:0; previous: 500, current: 461; changing to 500. This may result in incorrect timestamps in the output file.
[flv @ 0xc3d940] Non-monotonous DTS in output stream 0:0; previous: 500, current: 497; changing to 500. This may result in incorrect timestamps in the output file.
frame= 1112 fps= 31 q=-1.0 size=   14271kB time=00:00:42.16 bitrate=2772.7kbits/s speed=1.18x

这则讯息告诉我什么?

有什么需要改进的地方吗?

Is there anything to improve?

谢谢

推荐答案

您可以通过在摄像机输入之前添加 -use_wallclock_as_timestamps 1 来修复 DTS 错误，这同样适用于 thread_queue_size 错误，请在 -i 之前添加 -thread_queue_size 512 .

You can fix the DTS errors by adding -use_wallclock_as_timestamps 1 before your camera input, same goes for the thread_queue_size error, add -thread_queue_size 512 before -i.

例如

ffmpeg -use_wallclock_as_timestamps 1 -thread_queue_size 512 -i /dev/video0 -c copy test.mp4

---

Jann 的简要说明

---

A brief explanation from Jann

这迫使FFMPEG(确实是黑客)使用录音系统的时间戳，而不是尝试根据检测到的fps数.FPS检测臭名昭著例如，不准确.

This forces FFMPEG (a hack really) to use the recording SYSTEM's timestamp instead of trying to compute the time of the movie depending on the number of fps it detects. FPS detection is notoriously inaccurate, for instance.

当FFMPEG对此进行免费承认时，错误:从比特率估算持续时间，这可能是不准确的.

As FFMPEG freely admits when it gives this error: Estimating duration from bitrate, this may be inaccurate.

这也使 -t 标志(持续时间)也可以是实时的，而不是也取决于fps的计算.

This also enables the -t flag (duration) to be real-time as well, instead of also being dependent on the fps calculation.

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