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When the payload is a PSI Table (such as PAT/PMT), the payload pointer field will be available if the PUSI bit is set. However, if the payload is a PES packet, the payload pointer field is NOT available if the PUSI bit is set.
Source: ITU-T Rec. H.222.0 (02/00) "Information technology – Generic coding of moving pictures and associated audio information: systems", page 39 (semantic pagenr 19), section 2.4.3.3 (https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-H.222.0-200002-S!!PDF-E&type=items) — Preceding unsigned comment added by Moonsurfer1 (talk • contribs) 09:25, 9 June 2022 (UTC)[reply]
It seems to me that computer and IS people have a difficult time properly describing things like this. I can't tell from the article what a transport stream is in a physical sense. Is it just a data format that does not have any particular physical characteristics? Is it a disk file? Is it data that is moving from one place to another via some kind of cable? Or via RF transmission? Is it something else? Or some combination of the above? Where exactly does it fit in the physical world? If it can exist in two or more physical forms, which are more common? I have read this article and many other items on MPEG but am still confused on this point. Shouldn't an article like this, which is intended for the world at large and not just computer specalists, start out with a basic explanation? EPA3 (talk) 18:49, 16 September 2009 (UTC)[reply]
if every article start with a basic explanation in which amatures and nonspecialists can understand easily, then for each subject we should have a lot of unnecessary and repetitive text and articles. it is up to the reader to read prerequisites for the subject. and these prerequisites must be linked to, everywhere which is referenced to in the article. —Preceding unsigned comment added by 91.184.72.22 (talk) 12:08, 7 June 2010 (UTC)[reply]
Deleted the section because it is a spam magnet. Perhaps it can be brought back as "notable Programs that open TS files", and require any program to have at least 3 references and or wikipedia article? Daniel.Cardenas (talk) 17:58, 13 December 2010 (UTC) it looks like the section is back with comically few programs listed. It needs to be deleted, expanded, or have the selection criteria detailed.70.75.81.177 (talk) 18:09, 4 March 2012 (UTC)[reply]
Byte 1 is always 0x47.
However the next section comprises 2 bytes
| Name | Number ofbits |
Description |
|---|---|---|
| Transport Error Indicator (TEI) | 1 | Set by demodulator if can't correct errors in the stream, to tell the demultiplexer that the packet has an uncorrectable error [1] |
| Payload Unit Start Indicator | 1 | 1 means start of PES data or PSI otherwise zero only. |
| Transport Priority | 1 | 1 means higher priority than other packets with the same PID. |
| PID | 13 | Pack |
This is where the EXACT manner that the data is stored becomes important. While the data is a 16bit integer, remember those 16bits are divided evenly into 2 bytes. And just HOW they are divided into those 2 bytes will depend on how the program I'm about to write will have to go about reading the PID.
The 2 things to look at is BYTE ORDER, and BIT ORDER. The byte order will either be big endian (most significant byte first)or little endian (least significant byte first). And within each byte it can either be MSB first (bit7 first), or LSB first (bit0 first). And so there is a question of exactly which combination is used in an Mpeg2 Transport Stream. And the EXACT combination of these will become very tricky when trying to read data that is not a nice multiple of 8bits, in this case the PID which is 13 bits long, so while it crosses byte boundaries, it does NOT completely fill both bytes.
Therefore BOTH the BIT ORDER as well as BYTE ORDER will be EXTREMELY IMPORTANT for me to know, if I am to successfully write this program that I'm trying to write, who's purpose will be to extract the PID out of every packet of an MPEG2 Transport Stream file.
Please help. Thanks in advance.
76.104.145.19 (talk) 10:50, 17 August 2012 (UTC)[reply]
Nevermind the above question, I finally figured it out. I even created a sample program in VB6 that works. It reads and then outputs to a textfile the packet header data from a 188 byte MPEG2 Transport Stream (.ts) file. It's a very simple program, and doesn't really do a lot, but at least it works so far.
Private Type TsPacket SyncByte As Byte Flags1(1) As Byte Flags2 As Byte TsData(183) As Byte End Type Dim Flags1() As Byte Dim TEI As Boolean Dim PUSI As Boolean Dim TP As Boolean Dim PID As Integer Dim Flags2 As Byte Dim Scrambling As Byte Dim AdaptationFieldIndicator As Byte Dim ContinuityCounter As Byte Private Sub Form_Load() Dim TS() As TsPacket Open "C:\testvideo.ts" For Binary Access Read As #1 ReDim TS(LOF(1) \ 188 - 1) Get #1, 1, TS() Close #1 Open "C:\test.txt" For Output As #2 For n = 0 To UBound(TS) If TS(n).SyncByte = &H47 Then Flags1() = TS(n).Flags1() Flags2 = TS(n).Flags2 TEI = Flags1(0) And (2 ^ 7) PUSI = Flags1(0) And (2 ^ 6) TP = Flags1(0) And (2 ^ 5) PID = 0 For i = 0 To 4 PID = PID + ((Flags1(0) And (2 ^ (4 - i))) \ (2 ^ (4 - i))) * (2 ^ (12 - i)) Next i For i = 0 To 7 PID = PID + ((Flags1(1) And (2 ^ (7 - i))) \ (2 ^ (7 - i))) * (2 ^ (12 - (i + 5))) Next i Scrambling = (Flags2 And 64) \ 64 Scrambling = Scrambling + ((Flags2 And 128) \ 64) * 2 AdaptationFieldIndicator = (Flags2 And 16) \ 16 AdaptationFieldIndicator = AdaptationFieldIndicator + ((Flags2 And 32) \ 32) * 2 ContinuityCounter = Flags2 And 15 Print #2, TEI, PUSI, TP, GetHex(PID), Scrambling, AdaptationFieldIndicator, ContinuityCounter End If Next n Close #2 End Sub Private Function GetHex(ByVal Value As Integer) As String GetHex = String$(4 - Len(Hex(Value)), "0") & Hex(Value) End Function
76.104.145.19 (talk) 12:10, 17 August 2012 (UTC)[reply]
I don't think the mask given for PID is correct: 0x1fff00. I believe it should be 0x1fff, being the least significant 13 bits (big endian) Manolan1 (talk) 15:54, 22 April 2020 (UTC)[reply]
Ah, scratch that, I see what you have done! Manolan1 (talk) 15:56, 22 April 2020 (UTC)[reply]
References
Can the file/link be updated or corrected? Jeris0102 (talk) 20:33, 4 June 2014 (UTC)[reply]
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