教你如何从wireshark中的RTSP流媒体提取H.264码流数据

      相信很多做流媒体开发的朋友都在纠结如何抓取RTSP中的实际码流吧，因为从RTSP中提取h264文件不但可以让你详细分析码流，更让你能不通过任何其他方式分析网络流媒体的丢包、丢帧、卡顿、花屏等一些现实视频传输中经常遇到的问题。

      网络抓包工具神器wireshark一定是大部分同仁都钟意的一款很好用的网络抓包工具吧，下面就教你怎么使用wireshark从rtsp中提取h264码流吧，这能助你解决问题一臂之力！

     代码（来自互联网）：

-- Dump RTP h.264 payload to raw h.264 file (*.264)
-- According to RFC3984 to dissector H264 payload of RTP to NALU, and write it
-- to fromto.264 file. By now, we support single NALU,
-- STAP-A and FU-A format RTP payload for H.264.
-- You can access this feature by menu "Tools->Export H264 to file [HQX's plugins]"
-- Author: Huang Qiangxiong ([email protected])
-- change log:
-- 2014-04-22
-- Just can play
------------------------------------------------------------------------------------------------
do
-- for geting h264 data (the field's value is type of ByteArray)
local f_h264 = Field.new("h264")

-- menu action. When you click "Tools->Export H264 to file [HQX's plugins]" will run this function
local function export_h264_to_file()
-- window for showing information
local tw = TextWindow.new("Export H264 to File Info Win")
local pgtw = ProgDlg.new("Export H264 to File Process", "Dumping H264 data to file...")

-- add message to information window
function twappend(str)
tw:append(str)
tw:append("\n")
end

-- running first time for counting and finding sps+pps, second time for real saving
local first_run = true
-- variable for storing rtp stream and dumping parameters
local stream_infos = {}

-- trigered by all h264 packats
local my_h264_tap = Listener.new(tap, "h264")

-- get rtp stream info by src and dst address
function get_stream_info(pinfo)
local key = "from_" .. tostring(pinfo.src) .. "_" .. tostring(pinfo.src_port) .. "to" .. tostring(pinfo.dst) .. "_" .. tostring(pinfo.dst_port)
local stream_info = stream_infos[key]
if not stream_info then -- if not exists, create one
stream_info = { }
stream_info.filename = key.. ".264"
stream_info.file = io.open(stream_info.filename, "wb")
stream_info.counter = 0 -- counting h264 total NALUs
stream_info.counter2 = 0 -- for second time running
stream_infos[key] = stream_info
twappend("Ready to export H.264 data (RTP from " .. tostring(pinfo.src) .. ":" .. tostring(pinfo.src_port)
.. " to " .. tostring(pinfo.dst) .. ":" .. tostring(pinfo.dst_port) .. " to file:\n [" .. stream_info.filename .. "] ...\n")
end
return stream_info
end

-- write a NALU or part of NALU to file.
function write_to_file(stream_info, str_bytes, begin_with_nalu_hdr)
if first_run then
stream_info.counter = stream_info.counter + 1

if begin_with_nalu_hdr then
-- save SPS or PPS
local nalu_type = bit.band(str_bytes:byte(0,1), 0x1F)
if not stream_info.sps and nalu_type == 7 then
stream_info.sps = str_bytes
elseif not stream_info.pps and nalu_type == 8 then
stream_info.pps = str_bytes
end
end

else -- second time running
if stream_info.counter2 == 0 then
-- write SPS and PPS to file header first
if stream_info.sps then
stream_info.file:write("\00\00\00\01")
stream_info.file:write(stream_info.sps)
else
twappend("Not found SPS for [" .. stream_info.filename .. "], it might not be played!\n")
end
if stream_info.pps then
stream_info.file:write("\00\00\00\01")
stream_info.file:write(stream_info.pps)
else
twappend("Not found PPS for [" .. stream_info.filename .. "], it might not be played!\n")
end
end

if begin_with_nalu_hdr then
-- *.264 raw file format seams that every nalu start with 0x00000001
stream_info.file:write("\00\00\00\01")
end
stream_info.file:write(str_bytes)
stream_info.counter2 = stream_info.counter2 + 1

if stream_info.counter2 == stream_info.counter then
stream_info.file:flush()
twappend("File [" .. stream_info.filename .. "] generated OK!\n")
end
-- update progress window's progress bar
if stream_info.counter > 0 then pgtw:update(stream_info.counter2 / stream_info.counter) end
end
end

-- read RFC3984 about single nalu/stap-a/fu-a H264 payload format of rtp
-- single NALU: one rtp payload contains only NALU
function process_single_nalu(stream_info, h264)
write_to_file(stream_info, h264:tvb()():string(), true)
end

-- STAP-A: one rtp payload contains more than one NALUs
function process_stap_a(stream_info, h264)
local h264tvb = h264:tvb()
local offset = 1
repeat
local size = h264tvb(offset,2):uint()
write_to_file(stream_info, h264tvb(offset+2, size):string(), true)
offset = offset + 2 + size
until offset >= h264tvb:len()
end

-- FU-A: one rtp payload contains only one part of a NALU (might be begin, middle and end part of a NALU)
function process_fu_a(stream_info, h264)
local h264tvb = h264:tvb()
local fu_idr = h264:get_index(0)
local fu_hdr = h264:get_index(1)
if bit.band(fu_hdr, 0x80) ~= 0 then
-- start bit is set then save nalu header and body
local nalu_hdr = bit.bor(bit.band(fu_idr, 0xE0), bit.band(fu_hdr, 0x1F))
write_to_file(stream_info, string.char(nalu_hdr), true)
else
-- start bit not set, just write part of nalu body
end
write_to_file(stream_info, h264tvb(2):string(), false)
end

-- call this function if a packet contains h264 payload
function my_h264_tap.packet(pinfo,tvb)
local h264s = { f_h264() } -- using table because one packet may contains more than one RTP
for i,h264_f in ipairs(h264s) do
if h264_f.len < 2 then
return
end
local h264 = h264_f.value -- is ByteArray
local hdr_type = bit.band(h264:get_index(0), 0x1F)
local stream_info = get_stream_info(pinfo)

if hdr_type > 0 and hdr_type < 24 then
-- Single NALU
process_single_nalu(stream_info, h264)
elseif hdr_type == 24 then
-- STAP-A Single-time aggregation
process_stap_a(stream_info, h264)
elseif hdr_type == 28 then
-- FU-A
process_fu_a(stream_info, h264)
else
twappend("Error: unknown type=" .. hdr_type .. " ; we only know 1-23(Single NALU),24(STAP-A),28(FU-A)!")
end
end
end

-- close all open files
function close_all_files()
if stream_infos then
for id,stream in pairs(stream_infos) do
if stream and stream.file then
stream.file:close()
stream.file = nil
end
end
end
end

function my_h264_tap.reset()
-- do nothing now
end

function remove()
close_all_files()
my_h264_tap:remove()
end

tw:set_atclose(remove)

-- first time it runs for counting h.264 packets and finding SPS and PPS
retap_packets()
first_run = false
-- second time it runs for saving h264 data to target file.
retap_packets()
-- close progress window
pgtw:close()
end

-- Find this feature in menu "Tools->"Export H264 to file [HQX's plugins]""
register_menu("Export H264 to file [HQX's plugins]", export_h264_to_file, MENU_TOOLS_UNSORTED)
end

把代码保存成h264_export.lua文件，放到wireshark安装目录下，然后修改wireshark安装目录下的init.lua文件：

（1）若有disable_lua = true这样的行，则注释掉；

（2）在文件末加入dofile("h264_export.lua")

另外，在过滤栏目输入RTP，可以过滤所有的rtp报文，可以看到type为96.

点击：edit-->preference--》protocol-->H264,填上96，保存即可。

在打开包含H.264码流的抓包后，选菜单“Tools->Export H264 to file [HQX's plugins]”后，把抓包文件里的H.264码流自动导出到抓包文件所在目录（用户工作目录）里，名为from___to__.264的264裸码流文件里。（文件格式为每个NALU前加0x00000001分隔符）。

抓取了h.264文件之后，可以用Elecard打开h264文件进行码流分析