Infos sur les GOP(s)

[JC29]

Salut,

Connaissez-vous un petit soft (freeware/shareware), facile d'utilisation qui serait capable de lire un MPEG2 (surtout MPEG 2 HDV) et de restituer les informations suivantes :

- Débit binaire (CBR/VBR)
- Taille du GOP (valeur N)
- Fréquence GOP fermé
- Période d'image de référence (valeur M)
- Fréquence d'entête de Séquence
- Quantification base minimale sur :
- image I
- image B
- image P

J'ai testé MPEG parser mais je n'arrive pas explicitement à récupérer toutes les valeurs voulues.

En attendant, est-ce que quelqu'un connait précisément ces valeurs pour un MPEG 2 HDV 1080i ?

Merci d'avance

A+

[STEF]

et par la même occasion, si quelqu'un sait de quel type de time code il s'agit et comment il est enregistré, je suis preneur !

++

SteF

[vsb]

Envoyé par STEF

.....le time code ..... comment il est enregistré ...

Je n'ai pas de réponse certaine mais j'imagine que, tout comme pour le DV pour lequel on trouve un peu plus d'informations, il est imbriqué, réparti, dans le flux numérique global fourni ....

Mais ce n'est qu'une hypothèse ... vraisemblable

vsb

[7na-na]

Bonjour, TLM,

Une réponse partielle à valider et compléter par les spécialistes.

Pour un montage précis, on s'attend à ce que chaque image ait son propre timecode. Mais le flux MPEG rend cela difficile puisque la compression se fait en GOP (Group of pictures).

Dans le cas du timecode SMPTE RP-188, lors de la capture, l'encodeur MPEG HD insère le timecode au début de chaque GOP (GOP header). Cette méthode signifie qu'il y aura un timecode seulement toutes le x images (6 ou 12), donc l'équivalent d'une rupture de timecode. Ceci ne convient pas à une application broadcast.

Dans le cas du timecode SMPTE RP-328M, l'encodeur insère le timecode dans chaque image du flux MPEG. Cette information est contenue dans le user data. Au montage, avec un décodeur compatible, il sera donc possible de monter à l'image près. Ce même décodeur pourra mapper le timecode dans le signal HD selon les spécifications du SMPTE RP-188. On aura monté en se servant du user data, mais, au final, le timecode du flux MPEG sera inscrit dans les GOP headers.

Cela est-il correct et clair ? A vous, les spécialistes !

[JC29]

Bon je vous mets la lecture obtenue à partir de MPEG PARSER. Infos générales + 1er GOP

- Débit binaire (CBR/VBR) -> CBR
- Taille du GOP (valeur N) -> 12
- Fréquence GOP fermé ??????????????????? (may be 0 ???)
- Période d'image de référence (valeur M) ??????????????????
- Fréquence d'entête de Séquence ??????????????????

Si quelqu'un à la lecture de ce qui suit pouvait lever les 3 inconnues....

Merci d'avance.

GOP 000001 IBBPBBPBBPBB
GOP 000002 IBBPBBPBBPBB
GOP 000003 IBBPBBPBBPBB
GOP 000004 IBBPBBPBBPBB
GOP 000005 IBBPBBPBBPBB
GOP 000006 IBBPBBPBBPBB
GOP 000007 IBBPBBPBBPBB
GOP 000008 IBBPBBPBBPBB

etc...
Resolution: PAL
Frame Rate: 25
Drop Type: Non-drop frame
Data Start Time: 00:00:00.00 (25 fps)
Data End Time : 00:05:59.03 (25 fps)
Duration Time : 00:05:59.04 (25 fps)
Encode Type: MPEG 2
Size: 1440 x 1080
Aspect Ratio: 16 : 9
Bit rate: 25000000
Bitrate Type: Constant
Line21 Switch1: No
Line21 Switch2: No
Is PullDown: No
Picture Count: 8979
Pull Down Picture Count: 8979
Max number of pictures in GOP: 12
Sequence End Count: 0

Sequence header ( 1 )
Sequence Header Code: 179
Horizontal Size: 1440
Vertical Size: 1080
Aspect Ratio Code: 3 ( 16 : 9 )
Frame Rate Code: 3 ( 25 )
Bit Rate Value: 62500
Marker Bit: 1
"Video Buffering Verifier" Buffer Size Value: 448
Constrained Parameters Flag: 0
Load Intra Quantiser Matrix: Yes
Load Non Intra Quantiser Matrix: Yes

Sequence extension
Extension Start Code Identifier: 1
Profile and Level Indication: 70
Progressive Sequence: 0
Chroma Format: 1 ( 4:2:0 )
Horizontal Size Extension: 0
Vertical Size Extension: 0
Bit Rate Extension: 0
Marker Bit: 1
Vbv Buffer Size Extension: 0
Low Delay: 0
Frame Rate Extension N: 0
Frame Rate Extension D: 0

Sequence display extension
Extension Start Code Identifier: 2
Video Format: 0
Colour primaries: 1
Transfer characteristics: 1
Matrix coefficients: 1
Display horizontal size: 1440
Display vertical size: 1080

Group of pictures header ( 1 )
Group Start Code: 184
Drop Frame Flag: No
Time Code Hours: 0
Time Code Minutes: 0
Marker Bit: 1
Time Code Seconds: 0
Time Code Pictures: 0
Closed Gop: 0
Broken Link: 0

I - Frame
Temporal Reference: 2
VBV Delay: 22766
Full Pel Forward Vector: 0
Forward F Code: 0
Full Pel Backward Vector: 0
Backward F Code: 0
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 2
File position: 0
Coding extension :
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1
Intra VLC Format: 1
Alternate Scan: 1
Repeat First Field: 0
Chroma 420 Type: 0
Progressive Frame: 0
Composite Display Flag: 0
V-Axis: 0
Field Sequence: 0
Sub Carrier: 0
Burst Amplitude: 0
Sub Carrier Phase: 0

B - Frame
Temporal Reference: 0
VBV Delay: 20300
Full Pel Forward Vector: 0
Forward F Code: 7
Full Pel Backward Vector: 0
Backward F Code: 7
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 0
File position: 210785
Coding extension:
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1
Intra VLC Format: 1
Alternate Scan: 1
Repeat First Field: 0
Chroma 420 Type: 0
Progressive Frame: 0
Composite Display Flag: 0
V-Axis: 0
Field Sequence: 0
Sub Carrier: 0
Burst Amplitude: 0
Sub Carrier Phase: 0

B - Frame
Temporal Reference: 1
VBV Delay: 21147
Full Pel Forward Vector: 0
Forward F Code: 7
Full Pel Backward Vector: 0
Backward F Code: 7
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 1
File position: 306377

Coding extension:
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1
Intra VLC Format: 1
Alternate Scan: 1
Repeat First Field: 0
Chroma 420 Type: 0
Progressive Frame: 0
Composite Display Flag: 0
V-Axis: 0
Field Sequence: 0
Sub Carrier: 0
Burst Amplitude: 0
Sub Carrier Phase: 0

P - Frame
Temporal Reference: 5
VBV Delay: 21997
Full Pel Forward Vector: 0
Forward F Code: 7
Full Pel Backward Vector: 0
Backward F Code: 7
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 5
File position: 401865
Coding extension
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1
Intra VLC Format: 1
Alternate Scan: 1
Repeat First Field: 0
Chroma 420 Type: 0
Progressive Frame: 0
Composite Display Flag: 0
V-Axis: 0
Field Sequence: 0
Sub Carrier: 0
Burst Amplitude: 0
Sub Carrier Phase: 0


B - Frame
Temporal Reference: 3
VBV Delay: 20539
Full Pel Forward Vector: 0
Forward F Code: 7
Full Pel Backward Vector: 0
Backward F Code: 7
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 3
File position: 577484
Coding extension
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1
Intra VLC Format: 1
Alternate Scan: 1
Repeat First Field: 0
Chroma 420 Type: 0
Progressive Frame: 0
Composite Display Flag: 0
V-Axis: 0
Field Sequence: 0
Sub Carrier: 0
Burst Amplitude: 0
Sub Carrier Phase: 0

B - Frame
Temporal Reference: 4
VBV Delay: 21388
Full Pel Forward Vector: 0
Forward F Code: 7
Full Pel Backward Vector: 0
Backward F Code: 7
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 4
File position: 673020
Coding extension
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1
Intra VLC Format: 1
Alternate Scan: 1
Repeat First Field: 0
Chroma 420 Type: 0
Progressive Frame: 0
Composite Display Flag: 0
V-Axis: 0
Field Sequence: 0
Sub Carrier: 0
Burst Amplitude: 0
Sub Carrier Phase: 0

P - Frame
Temporal Reference: 8
VBV Delay: 22239
Full Pel Forward Vector: 0
Forward F Code: 7
Full Pel Backward Vector: 0
Backward F Code: 7
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 8
File position: 768454
Coding extension
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1
Intra VLC Format: 1
Alternate Scan: 1
Repeat First Field: 0
Chroma 420 Type: 0
Progressive Frame: 0
Composite Display Flag: 0
V-Axis: 0
Field Sequence: 0
Sub Carrier: 0
Burst Amplitude: 0
Sub Carrier Phase: 0

B - Frame
Temporal Reference: 6
VBV Delay: 20783
Full Pel Forward Vector: 0
Forward F Code: 7
Full Pel Backward Vector: 0
Backward F Code: 7
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 6
File position: 944024
Coding extension
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1
Intra VLC Format: 1
Alternate Scan: 1
Repeat First Field: 0
Chroma 420 Type: 0
Progressive Frame: 0
Composite Display Flag: 0
V-Axis: 0
Field Sequence: 0
Sub Carrier: 0
Burst Amplitude: 0
Sub Carrier Phase: 0

B - Frame
Temporal Reference: 7
VBV Delay: 21637
Full Pel Forward Vector: 0
Forward F Code: 7
Full Pel Backward Vector: 0
Backward F Code: 7
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 7
File position: 1039347
Coding extension
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1
Intra VLC Format: 1
Alternate Scan: 1
Repeat First Field: 0
Chroma 420 Type: 0
Progressive Frame: 0
Composite Display Flag: 0
V-Axis: 0
Field Sequence: 0
Sub Carrier: 0
Burst Amplitude: 0
Sub Carrier Phase: 0

P - Frame
Temporal Reference: 11
VBV Delay: 22463
Full Pel Forward Vector: 0
Forward F Code: 7
Full Pel Backward Vector: 0
Backward F Code: 7
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 11
File position: 1135698
Coding extension
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1
Intra VLC Format: 1
Alternate Scan: 1
Repeat First Field: 0
Chroma 420 Type: 0
Progressive Frame: 0
Composite Display Flag: 0
V-Axis: 0
Field Sequence: 0
Sub Carrier: 0
Burst Amplitude: 0
Sub Carrier Phase: 0

B - Frame
Temporal Reference: 9
VBV Delay: 21071
Full Pel Forward Vector: 0
Forward F Code: 7
Full Pel Backward Vector: 0
Backward F Code: 7
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 9
File position: 1309002
Coding extension
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1

B - Frame
Temporal Reference: 10
VBV Delay: 21906
Full Pel Forward Vector: 0
Forward F Code: 7
Full Pel Backward Vector: 0
Backward F Code: 7
Extra Bit Picture: 0
Extra Information Picture: 0
Display Order: 10
File position: 1405026
Coding extension
Intra DC Precision: 2 ( 10 bit )
Picture Structure: 3 ( Frame picture )
Top Field First: 1
Frame Pred Frame DCT: 0
Concealment Motion Vectors: 0
Q-Scale Type: 1
Intra VLC Format: 1
Alternate Scan: 1
Repeat First Field: 0
Chroma 420 Type: 0
Progressive Frame: 0
Composite Display Flag: 0
V-Axis: 0
Field Sequence: 0
Sub Carrier: 0
Burst Amplitude: 0
Sub Carrier Phase: 0

A+