抓取一个包含H.264 Payload RTP包的SIP会话或RTSP会话后，用Wireshark的Play功能只能播放声音，不能播放视频。把RTP payload直接导出成文件后也是不能直接播放的，因为H.264 over RTP封包是符合RFC3984规范的，必须按照该规范把H.264数据取出来后，组成NALU，放到avi/mp4或裸码流文件等容器里后才能播放。
本人写了一个wireshark插件，可以在打开包含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（工作目录）里，名为from_<RTP流源ip>_<RTP流源端口>_to_<RTP流目的ip>_<RTP流目的端口>.264的264裸码流文件里。（文件格式为每个NALU前加0x00000001分隔符）。
本程序可以识别RFC3984里提到的三种H.264 over RTP封装，分别是Single NALU（一个RTP含一个NALU）、STAP-A（一个RTP包含多个NALU）、FU-A（一个NALU分布到多个RTP包）三种封装格式，且会自动把SPS和PPS放到裸码流文件头部。
Lua脚本如下：
-- 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 from<sourceIp_sourcePort>to<dstIp_dstPort>.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 (qiangxiong.huang@gmail.com)
-- change log:
-- 2012-03-13
-- 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")
重新打开wirekshark就能使用该功能了。
另外，264裸码流文件一般播放器不一定能播放，推荐使用ffmpeg的ffplay播放，或用ffmpeg转成通用文件格式播放。