为什么无法接收 .avi 视频文件的 rtp 流？

Question

在ffmpeg streamingGuide 中，它写道：

ffmpeg -re -f lavfi -i aevalsrc="sin(400*2*PI*t)" -ar 8000 -f mulaw -f rtp rtp://127.0.0.1:1234 &
ffplay rtp://127.0.0.1:1234

我想用真实的视频文件来代替人工信号。 然后我在终端A写下：

ffmpeg -re -i outputFile.avi -f mulaw -f rtp rtp://127.0.0.1:1234

它似乎正在工作： 帧信息正在计数。下面是最后A航站楼的信息：

frame=  309 fps= 29 q=31.0 Lsize=     931kB time=00:00:10.30 bitrate= 740.8kbits/s     video:922kB audio:0kB subtitle:0 global headers:0kB muxing overhead 1.030813%

当终端 A 的帧仍在计数（未完成）时，我在终端 B 键入以下内容：

ffplay rtp://127.0.0.1:1234

但它不起作用： 错误信息是：

[udp @ 0x7fb370001500] bind failed: Address already in useB f=0/0   
rtp://127.0.0.1:1234: Input/output error

为什么？

[更新 1] 按照 Camille Goudeseune 的指示 我使用了 foo.sdp
ffmpeg 终端的输入是：

ffmpeg -re -i out.avi -f mulaw -f rtp rtp://127.0.0.1:1235

ffplay的终端是：

ffplay -i foo.sdp

ffplay终端显示很多错误，没有图片。

  libpostproc    52.  2.100 / 52.  2.100
[sdp @ 0x7fafdc0008c0] Undefined type (30)    0KB sq=    0B f=0/0   
[sdp @ 0x7fafdc0008c0] nal size exceeds length: 25453 86 0B f=0/0   
[sdp @ 0x7fafdc0008c0] Consumed more bytes than we got! (-25367)
[sdp @ 0x7fafdc0008c0] nal size exceeds length: 25453 86
[sdp @ 0x7fafdc0008c0] Consumed more bytes than we got! (-25367)
[sdp @ 0x7fafdc0008c0] Unhandled type (27) (See RFC for implementation details
[sdp @ 0x7fafdc0008c0] Undefined type (31)    0KB sq=    0B f=0/0   
[sdp @ 0x7fafdc0008c0] Unhandled type (27) (See RFC for implementation details
[sdp @ 0x7fafdc0008c0] nal size exceeds length: 62414 6130B f=0/0   
[sdp @ 0x7fafdc0008c0] Consumed more bytes than we got! (-61801)
[sdp @ 0x7fafdc0008c0] nal size exceeds length: 62414 613
[sdp @ 0x7fafdc0008c0] Consumed more bytes than we got! (-61801)
[h264 @ 0x7fafdc003020] non-existing PPS referencedq=    0B f=0/0   
[h264 @ 0x7fafdc003020] non-existing PPS 0 referenced
[h264 @ 0x7fafdc003020] decode_slice_header error
[h264 @ 0x7fafdc003020] Invalid mix of idr and non-idr slices
[sdp @ 0x7fafdc0008c0] Undefined type (31)    0KB sq=    0B f=0/0   
[sdp @ 0x7fafdc0008c0] Unhandled type (29) (See RFC for implementation details
[sdp @ 0x7fafdc0008c0] Unhandled type (26) (See RFC for implementation details
[sdp @ 0x7fafdc0008c0] Unhandled type (27) (See RFC for implementation details
    Last message repeated 2 times  0KB vq=    0KB sq=    0B f=0/0   
[sdp @ 0x7fafdc0008c0] Undefined type (31)
[sdp @ 0x7fafdc0008c0] Unhandled type (26) (See RFC for implementation details
[sdp @ 0x7fafdc0008c0] Unhandled type (25) (See RFC for implementation details
[h264 @ 0x7fafdc003020] insane cropping not completely supported, this could look slightly wrong ... (left: 2, top: 2)
[h264 @ 0x7fafdc003020] illegal aspect ratio
[h264 @ 0x7fafdc003020] missing picture in access unit with size 84589
[h264 @ 0x7fafdc003020] Partitioned H.264 support is incomplete
[h264 @ 0x7fafdc003020] insane cropping not completely supported, this could look slightly wrong ... (left: 2, top: 2)
[h264 @ 0x7fafdc003020] illegal aspect ratio
[h264 @ 0x7fafdc003020] insane cropping not completely supported, this could look slightly wrong ... (left: 2, top: 2)
[h264 @ 0x7fafdc003020] illegal aspect ratio
[h264 @ 0x7fafdc003020] no frame!
[h264 @ 0x7fafdc003020] RTP: missed 2563 packetsB sq=    0B f=0/0   
[sdp @ 0x7fafdc0008c0] Undefined type (30)
    Last message repeated 1 times
[sdp @ 0x7fafdc0008c0] Undefined type (31)

Answer 1

ffplay rtp://127.0.0.1:1234 将开始在 UDP 端口 1234 上侦听传入的 RTP 流量。

在任何给定时间，只有一个应用程序可以监听主机上的任何给定端口。

错误“绑定失败：地址已在使用”表明另一个应用程序已经在侦听端口 1234。 可能您仍在运行测试中的脚本？

要么停止阻塞端口的应用程序，要么使用其他端口。

Answer 2

用ffplay -i foo.sdp代替ffplay rtp://127.0.0.1:1235。

创建本地文件foo.sdp，将ffmpeg的文本输出粘贴到SDP:行之后，例如：

v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 127.0.0.1
t=0 0
a=tool:libavformat 55.2.100
m=video 1235 RTP/AVP 96
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1

.sdp 文件包含 rtp 地址，因此您也无需指定 rtp://...。