寻找 T.38 库
我正在尝试实现一个与传真一起使用的系统。 我们有一个网关、电话至 T.38（IP 传真）。 我需要一个库，让我可以将 T.38 转换为 TIFF 图像。 我在 Mac 上执行此操作，我们使用 C、C++、php、java。
一个可以悄悄地将 T.38 转换为 T.37（通过电子邮件发送传真）的程序也同样有效。
有人知道其中任何一个吗？
I'm trying to implement a system that works with faxes. We have a gatewary, phone to T.38 (fax over IP). I need a library that will let me do the other end, T.38 to TIFF image. I'm doing this on a mac, and we work with C, C++, php, java.
A program that will quietly turn T.38 into T.37 (fax over email) would work just as well.
Does anyone know of either of these?
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T.38 网关实际上只是调制解调器部分，用于获取电话线上的传真模拟“音频”数据，并将其转换为较低级别 T.30 HDLC 数据的直接二进制数字数据包流。 T.38 标准确实指定了某种级别的应用程序级解码，以延长某些传真确认握手中的计时器......实际上，T.38 网关在其一端与电话另一端的传真机购买了一些时间当东西通过 IP 网络时进行呼叫...特别是如果存在数据包丢失等情况。但是，所有这些都发生在 T.38 网关和传真机之间...而不是针对 IP 网络。
因此，如果您确实想要查看 T.38 网关的 IP 数据包端，并且确实想要访问传真文档图像并将其呈现为 TIFF，那么您真正需要的是 T.30 传真终止因为 T.30 指定了 HDLC 数据的格式以及如何编码/解码该内容。 实际上，您必须实现传真机的逻辑以将文档捕获为 TIFF，就像真正的传真机捕获图像并打印到纸张上一样。
即：您真正需要的是 T.30 实现，而不是 T.38 实现。 请注意，T.30 标准的一部分还引用了 T.4，它描述了如何在 T.30 的上下文中压缩实际图像数据。
相对于从 T.38 到 T.37，虽然我认为这在理论上是可能的，但请理解，就像 T.38 一样，T.37 标准假设此类网关的一端是模拟域。 也就是说，T.37 标准指定了如何从模拟到电子邮件消息，就像 T.38 从模拟到实时数字数据包流一样。 在标准的背景下，没有从 T.38 到 T.37 的“双跳”来获取传真图像......所以我认为找到现有的实现似乎不太可能。
最后，您需要的是 T.30 传真终端实施，因为您正在通话的 T.38 网关已经为您完成了调制解调器部分。 或者，另一种看待此问题的方式是您需要 T.37 网关而不是 T.38 网关。
A T.38 gateway is really just the modem section to take FAX analog "audio" data on the phone line and turns it a straight binary digital packet stream of lower level T.30 HDLC data. The T.38 standard does specify some level of application level decoding to extend the timers in certain FAX acknolwedgement handshakes....in effect the T.38 gateway buys some time at his end with the FAX machine at the other end of the phone call while stuff makes it through the IP network...especially if there is packet loss etc. However, all of that is going on between the T.38 gateway and the FAX machine....not towards the IP network.
So, if you really want to peer into the IP packet end of the T.38 gateway and actually want to get access to the FAX'ed document images and render that as TIFF, what you really are looking for is T.30 FAX Termination since T.30 specifies the format of the HDLC data and how to encode/decode that content. In effect, you have to implement the FAX machine's logic to capture the documents into TIFF in the same way that a real FAX machine would have captured the images and printed to paper.
ie: What you are really for is a T.30 implementation, not a T.38 implementation. Note that part of the the T.30 standard also references T.4 which describes how the the actual image data is compressed within the context of T.30.
Relative to going from T.38 to T.37, while I suppose that would be theoretically possible, understand that just like T.38, the T.37 standard assumes that one end of such a gateway is the analog domain. That is, the standard of T.37 specifies how to go from analog to an email message in the same way that T.38 goes from analog to real-time digital packet stream. In the context of the standards there is no "double hop" from T.38 to T.37 to get to your FAX images....so I think finding an existing implementation seems unlikely.
In the end, what you need is a T.30 FAX termination implementation since the T.38 gateway you are talking to is already doing the modem part for you. Alternatively, another way of looking at this is that you want a T.37 gateway instead of a T.38 gateway.
Asterisk 开源 PBX 使用 SpanDSP 库来实现传真。 看起来该库有 模块 来处理 T.38 以及 Jeff 提到的 InSciTek 的其他协议。
Asterisk the open source PBX uses the SpanDSP library to implement faxing. It looks like that library has modules to handle T.38 and the other protocols InSciTek Jeff mentioned.
OPAL是一个支持T.38的库（最多只能到14400）（也可以使用spansp来处理G711 音频包含传真音）。 商业选择也存在，主要来自 Dialogic 和 Commetrex。
OPAL is a library that supports T.38 (Only up to 14400) (It can also use spandsp to deal with G711 audio containing fax tones). Commercial options also exist, mostly from Dialogic and Commetrex.
如果您愿意在某个地方使用 Linux，Hylafax 可能适合您。
我使用星号+iaxmodem+hylafax。 Hylafax 旨在接收/发送传真。 收到的传真将保存为 tiff 或 pdf，或发送到您自己制作的任意脚本进行处理。 Hylafax 希望使用真正的调制解调器。 Iaxmodem 模拟真实的调制解调器，同时实际上是与 asterisk 的 IAX2（voip 协议，如 sip）连接。
如果你真的很硬核，你可以考虑从 hylafax 中提取“转换”部分，并将其转换为一个库供你自己在 Mac 上使用。 它是开源的。
Hylafax may work for you, if you're willing to use linux somewhere.
I use asterisk + iaxmodem + hylafax. Hylafax is designed to receive/send faxes. Received faxes are saved as tiffs or pdf's or sent to an arbitrary script of your own making for processing. Hylafax expects to use real modems. Iaxmodem simulates a real modem while really being an IAX2 (voip protocol like sip) connection to asterisk.
If you're really hardcore, you could look at extracting the 'conversion' part out of hylafax and turning it into a library for your own use on the mac. It is open source.