[Gambas-user] reading files
Shane
buster6seven at ...626...
Thu Jul 20 03:15:55 CEST 2017
thanks tony sounds like just what i needed i will take a look
cheers
On 19/07/17 22:34, Tony Morehen wrote:
> I've attached an archive containing the code I use to read v1 and v2
> MP3 tags and other MP3 info including bitrates (fixed and VBR),
> sampling rates and number of channels. v1 tags are pretty
> staightforward to read if you don't try to read the structure
> directly, but by each element of the structure at a time. Some tips:
>
> 1) Numeric elements (bytes, bytearrays, shorts, integers, longs) can
> be read directly from the stream. ie (4 byte Integer) = Read #Stream
> As Integer. Gambas can handle little endian/big endian issues.
>
> 2) Fixed length strings must be handled in a two stage process. First,
> the required string length number of bytes is read into a byte array.
> This byte array is then converted to a string. Sample code:
>
> Dim Bytes As New Byte[StringLength]
> Bytes.Read(Stream)
> FixedString = Bytes.ToString()
>
> Note: Bytes.ToString stops the string conversion at the first null or
> at the end of the array. Therfore, you don't have to worry about
> null-terminated strings.
>
> v2 tags are more complicated, particularly since the tags can be
> ascii, either kind of utf16, or utf8 encoding. The code I sent has
> been tested with over 10,000 mp3 files has seems to have no issues.
>
>
> On 2017-07-19 12:33 AM, Shane wrote:
>> thank you Gian i did take a rest and read but alas it did not help
>>
>> as far as i see it he is saying don't use binary file for fixed
>> length strings
>>
>> but as this is an mp3 file tag witch i have no control i am doomed
>>
>>
>>
>> On 18/07/17 19:22, Gianluigi wrote:
>>> Why do not you take a moment of rest and read what Tobias Boege
>>> recommend
>>> me in the discussion [0] I told you here [1]?
>>>
>>> [0]
>>> http://gambas.8142.n7.nabble.com/Random-access-files-with-fixed-length-string-td50880.html
>>>
>>> [1] http://gambas.8142.n7.nabble.com/vb-code-td59764.html
>>>
>>> 2017-07-18 9:04 GMT+02:00 Shane <buster6seven at ...626...>:
>>>
>>>> I am very confused from the docs
>>>>
>>>> _Variable_ *= READ* [ *#* _Stream_ ] *AS* _Datatype_
>>>>
>>>> _Variable_ *= READ* [ *#* _Stream_ *,* ] _Length_
>>>>
>>>> so wouldn't it be_
>>>> _
>>>>
>>>> IDtag = read #hfile as ID3v1_TAG ?
>>>>
>>>> with doesn't work by the way
>>>>
>>>>
>>>>
>>>> On 18/07/17 12:44, nando_f at ...951... wrote:
>>>>
>>>>> I think
>>>>> Read #hfile, IDtag, ID3v1_TAG
>>>>> should be
>>>>> Read #hfile, IDtag as ID3v1_TAG
>>>>>
>>>>>
>>>>> --
>>>>> Open WebMail Project (http://openwebmail.org)
>>>>>
>>>>>
>>>>> ---------- Original Message -----------
>>>>> From: Shane <buster6seven at ...626...>
>>>>> To: gambas-user at lists.sourceforge.net
>>>>> Sent: Tue, 18 Jul 2017 10:50:43 +1000
>>>>> Subject: Re: [Gambas-user] reading files
>>>>>
>>>>> i don't know what i am doing wrong
>>>>>> Public Struct ID3v1_TAG '(128 bytes)
>>>>>> Tag[3] As String 'always TAG
>>>>>> Title[30] As String 'title, 30 characters
>>>>>> Artist[30] As String 'artist, 30 characters
>>>>>> Album[30] As String 'album, 30 characters
>>>>>> Year[4] As String 'year, 4 characters
>>>>>> Comment[30] As String 'comment, 30 characters
>>>>>> (or 28 if
>>>>>> track# included)
>>>>>> Genre As Byte 'genre, 255 for none defined
>>>>>> End Struct
>>>>>>
>>>>>> Private Sub GetID3v1(File As String)
>>>>>> Dim IDtag As ID3v1_TAG
>>>>>> Dim hfile As File
>>>>>>
>>>>>> hfile = Open File For Read
>>>>>>
>>>>>> '
>>>>>> 'read the tag
>>>>>> ' seek to end of less tag size
>>>>>>
>>>>>> Read #hfile, IDtag, ID3v1_TAG
>>>>>>
>>>>>> here i get IDtag is NULL
>>>>>>
>>>>>> On 18/07/17 05:05, nando_f at ...951... wrote:
>>>>>>
>>>>>>> Yes it is possible, I do it. here is some code (incomplete)
>>>>>>>
>>>>>>> -Nando (Canada)
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> ' top of class file
>>>>>>> Public Struct recstruc
>>>>>>> _a as integer
>>>>>>> _b as integer
>>>>>>> _c as integer
>>>>>>> end struct
>>>>>>>
>>>>>>>
>>>>>>> ' a function
>>>>>>> public function openAfile(filename as string) as file
>>>>>>>
>>>>>>> dim hfile as file
>>>>>>> dim arec as recstruc
>>>>>>>
>>>>>>> hfile = open filename for read write create
>>>>>>>
>>>>>>> with arec 'some values to write.
>>>>>>> ._a = 1
>>>>>>> ._b = 22
>>>>>>> ._c = 333
>>>>>>> end with
>>>>>>>
>>>>>>> write #hfile, arec as recstruc
>>>>>>>
>>>>>>> 'if you position the hfile pointer back to zero, you can...
>>>>>>> read #hfile, arec as recstruc
>>>>>>>
>>>>>>> close #hfile
>>>>>>>
>>>>>>> end
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Open WebMail Project (http://openwebmail.org)
>>>>>>>
>>>>>>>
>>>>>>> ---------- Original Message -----------
>>>>>>> From: T Lee Davidson <t.lee.davidson at ...626...>
>>>>>>> To: gambas-user at lists.sourceforge.net
>>>>>>> Sent: Sun, 16 Jul 2017 12:42:35 -0400
>>>>>>> Subject: Re: [Gambas-user] reading files
>>>>>>>
>>>>>>> On 07/16/2017 06:57 AM, Shane wrote:
>>>>>>>>> given this example
>>>>>>>>>
>>>>>>>>> PRIVATE SUB BinaryRead(FilePath AS String)
>>>>>>>>> DIM binaryFile AS File
>>>>>>>>> DIM i AS Integer
>>>>>>>>> DIM b AS Byte
>>>>>>>>> DIM s AS Short
>>>>>>>>> DIM s1 AS String
>>>>>>>>> DIM s2 AS String
>>>>>>>>> ' Read binary file
>>>>>>>>> binaryFile = OPEN FilePath FOR READ
>>>>>>>>> READ #binaryFile, i
>>>>>>>>> READ #binaryFile, b
>>>>>>>>> READ #binaryFile, s
>>>>>>>>> READ #binaryFile, s1
>>>>>>>>> READ #binaryFile, s2
>>>>>>>>> CLOSE #binaryFile
>>>>>>>>> ' Display results
>>>>>>>>> PRINT i
>>>>>>>>> PRINT b
>>>>>>>>> PRINT s
>>>>>>>>> PRINT s1
>>>>>>>>> PRINT s2
>>>>>>>>> END
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> is there a way for gambas to read a struct of all these variables
>>>>>>>>> in one read ?
>>>>>>>>>
>>>>>>>>> You may have hinted at the solution within your question. Have
>>>>>>>>> you
>>>>>>>> considered
>>>>>>>> using a Structure?
>>>>>>>>
>>>>>>>> http://gambaswiki.org/wiki/lang/read :
>>>>>>>> "... reads the stream Stream as binary data whose type is
>>>>>>>> specified by
>>>>>>>> the
>>>>>>>> Datatype argument."
>>>>>>>>
>>>>>>>> "The returned datatype can be one of the following: NULL, Boolean,
>>>>>>>> Byte, Short,
>>>>>>>> Integer, Long, Pointer, Single, Float, Date, String,
>>>>>>>> Variant, any
>>>>>>>> Array,
>>>>>>>> Collection or structure."
>>>>>>>>
>>>>>>>> http://gambaswiki.org/wiki/lang/structdecl
>>>>>>>>
>>>>>>>> --
>>>>>>>> Lee
>>>>>>>>
>>>>>>>> ------------------------------------------------------------
>>>>>>>> ------------------
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>>>>>>>>
>>>>>>> ------- End of Original Message -------
>>>>>>>
>>>>>>>
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>>>>> ------- End of Original Message -------
>>>>>
>>>>>
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