现在的DVD机普遍都能播放U盘上视频文件，一般也支持SRT、SUB等字幕。但在某些播放机上SRT字幕字体偏小，无法看清，也无法调节字体大小。SUB字幕是一种图形字幕格式，大小字体等都较好控制，所以把SRT转换成SUB格式即可解决上述问题。
字幕格式介绍可参考：http://zh.wikipedia.org/wiki/字幕格式
从网上找了一大堆字幕转换工具，最后发现还是Text2VobSub比较好用。Text2VobSub是国外软件，最新版本3.4。下载地址：
http://www.trustfm.net/divx/SoftwareTxt2Vobsub.php?page=Txt2VobsubDownload&b2=1
使用easy-share方式下载还比较快。
以下是运行截图：（稍后补上）
使用还要注意一些问题：
帧率设置：
一般设为25，不然在某些播放机上会出问题。
SRT字幕编码：
当前只支持ANSI编码，UTF-8、UCS-2都不支持。如果无法打开字幕有可能是编码问题，用记事本打开然后再另存为ANSI编码即可。
调色板：
字幕颜色可能在PC上正常，但在DVD上颜色不正常，甚至很难分辨。在“Color Options”里选择“DVD ONLY”仍然不正常。看了一下资料，调色板内容是在.IDX文件中定义的。具体的也不想再研究了，干脆拿来主义，把别人的.IDX内容复制过来。试了一下，还比较奏效！
以下是复制来的.IDX文件头：
字幕格式介绍可参考：http://zh.wikipedia.org/wiki/字幕格式
从网上找了一大堆字幕转换工具，最后发现还是Text2VobSub比较好用。Text2VobSub是国外软件，最新版本3.4。下载地址：
http://www.trustfm.net/divx/SoftwareTxt2Vobsub.php?page=Txt2VobsubDownload&b2=1
使用easy-share方式下载还比较快。
以下是运行截图：（稍后补上）
使用还要注意一些问题：
帧率设置：
一般设为25，不然在某些播放机上会出问题。
SRT字幕编码：
当前只支持ANSI编码，UTF-8、UCS-2都不支持。如果无法打开字幕有可能是编码问题，用记事本打开然后再另存为ANSI编码即可。
调色板：
字幕颜色可能在PC上正常，但在DVD上颜色不正常，甚至很难分辨。在“Color Options”里选择“DVD ONLY”仍然不正常。看了一下资料，调色板内容是在.IDX文件中定义的。具体的也不想再研究了，干脆拿来主义，把别人的.IDX内容复制过来。试了一下，还比较奏效！
以下是复制来的.IDX文件头：
# VobSub index file, v7 (do not modify this line!)
#
# To repair desyncronization, you can insert gaps this way:
# (it usually happens after vob id changes)
#
# delay: [sign]hh:mm:ss:ms
#
# Where:
# [sign]: +, - (optional)
# hh: hours (0 <= hh)
# mm/ss: minutes/seconds (0 <= mm/ss <= 59)
# ms: milliseconds (0 <= ms <= 999)
#
# Note: You can't position a sub before the previous with a negative value.
#
# You can also modify timestamps or delete a few subs you don't like.
# Just make sure they stay in increasing order.
# Settings
# Original frame size
size: 720x576
# Origin, relative to the upper-left corner, can be overloaded by aligment
org: 0, 0
# Image scaling (hor,ver), origin is at the upper-left corner or at the alignment coord (x, y)
scale: 100%, 100%
# Alpha blending
alpha: 100%
# Smoothing for very blocky p_w_picpaths (use OLD for no filtering)
smooth: OFF
# In millisecs
fadein/out: 50, 50
# Force subtitle placement relative to (org.x, org.y)
align: OFF at LEFT TOP
# For correcting non-progressive desync. (in millisecs or hh:mm:ss:ms)
# Note: Not effective in DirectVobSub, use "delay: ... " instead.
time offset: 0
# ON: displays only forced subtitles, OFF: shows everything
forced subs: OFF
# The original palette of the DVD
palette: 000000, 1f1f1f, ffffff, e63f07, 7e7e7e, bebebe, 14bef3, ea12eb, faff1a, 000070, 067506, 731f03, 095f78, 750975, 7c950b, ffffff
# Custom colors (transp idxs and the four colors)
custom colors: OFF, tridx: 1000, colors: e63f07, ffffff, 000000, 1f1f1f
#
# To repair desyncronization, you can insert gaps this way:
# (it usually happens after vob id changes)
#
# delay: [sign]hh:mm:ss:ms
#
# Where:
# [sign]: +, - (optional)
# hh: hours (0 <= hh)
# mm/ss: minutes/seconds (0 <= mm/ss <= 59)
# ms: milliseconds (0 <= ms <= 999)
#
# Note: You can't position a sub before the previous with a negative value.
#
# You can also modify timestamps or delete a few subs you don't like.
# Just make sure they stay in increasing order.
# Settings
# Original frame size
size: 720x576
# Origin, relative to the upper-left corner, can be overloaded by aligment
org: 0, 0
# Image scaling (hor,ver), origin is at the upper-left corner or at the alignment coord (x, y)
scale: 100%, 100%
# Alpha blending
alpha: 100%
# Smoothing for very blocky p_w_picpaths (use OLD for no filtering)
smooth: OFF
# In millisecs
fadein/out: 50, 50
# Force subtitle placement relative to (org.x, org.y)
align: OFF at LEFT TOP
# For correcting non-progressive desync. (in millisecs or hh:mm:ss:ms)
# Note: Not effective in DirectVobSub, use "delay: ... " instead.
time offset: 0
# ON: displays only forced subtitles, OFF: shows everything
forced subs: OFF
# The original palette of the DVD
palette: 000000, 1f1f1f, ffffff, e63f07, 7e7e7e, bebebe, 14bef3, ea12eb, faff1a, 000070, 067506, 731f03, 095f78, 750975, 7c950b, ffffff
# Custom colors (transp idxs and the four colors)
custom colors: OFF, tridx: 1000, colors: e63f07, ffffff, 000000, 1f1f1f
