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author | Anders Broman <anders.broman@ericsson.com> | 2007-04-02 06:49:28 +0000 |
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committer | Anders Broman <anders.broman@ericsson.com> | 2007-04-02 06:49:28 +0000 |
commit | 98cc46f2a4ce695f8a38cbe56c8d87a1cf6873dd (patch) | |
tree | 5e17b5ef6e11ef9784b171aa0eb499a3638bcca2 /epan/dissectors/packet-h263.c | |
parent | 0104002d2ef03f3fb71558f4b2dd3a7f2b3bdaea (diff) |
Add comments
svn path=/trunk/; revision=21299
Diffstat (limited to 'epan/dissectors/packet-h263.c')
-rw-r--r-- | epan/dissectors/packet-h263.c | 146 |
1 files changed, 139 insertions, 7 deletions
diff --git a/epan/dissectors/packet-h263.c b/epan/dissectors/packet-h263.c index 683cae23ac..e5ae20c6dd 100644 --- a/epan/dissectors/packet-h263.c +++ b/epan/dissectors/packet-h263.c @@ -573,6 +573,8 @@ dissect_h263_picture_layer( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32 source_format; guint32 ufep; guint32 picture_coding_type; + guint32 PB_frames_mode = 0; + guint32 cpm; if(is_rfc4626){ /* PC 1000 00xx */ @@ -625,7 +627,7 @@ dissect_h263_picture_layer( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, h263_proto_tree_add_bits( tree, hf_h263_optional_advanced_prediction_mode, tvb, offset_in_bits, 1, NULL); offset_in_bits++; /* Bit 13: Optional PB-frames mode (see Annex G), "0" normal I- or P-picture, "1" PB-frame.*/ - h263_proto_tree_add_bits( tree, hf_h263_PB_frames_mode, tvb, offset_in_bits, 1, NULL); + h263_proto_tree_add_bits( tree, hf_h263_PB_frames_mode, tvb, offset_in_bits, 1, &PB_frames_mode); offset_in_bits++; }else{ /* Extended PTYPE @@ -734,20 +736,150 @@ dissect_h263_picture_layer( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, * (see 5.1.20 and 5.1.21). If PLUSPTYPE is present, then CPM follows * immediately after PLUSPTYPE in the picture header. */ - h263_proto_tree_add_bits( tree, hf_h263_cpm, tvb, offset_in_bits, 1, NULL); + h263_proto_tree_add_bits( tree, hf_h263_cpm, tvb, offset_in_bits, 1, &cpm); offset_in_bits++; - h263_proto_tree_add_bits( tree, hf_h263_psbi, tvb, offset_in_bits, 2, NULL); - offset_in_bits = offset_in_bits +2; + /* 5.1.21 Picture Sub-Bitstream Indicator (PSBI) (2 bits) + * only present if Continuous Presence Multipoint and Video + * Multiplex mode is indicated by CPM. + */ + if(cpm==1){ + h263_proto_tree_add_bits( tree, hf_h263_psbi, tvb, offset_in_bits, 2, NULL); + offset_in_bits = offset_in_bits +2; + } + /* TODO Add the rest of the fields */ + /* 5.1.5 Custom Picture Format (CPFMT) (23 bits) + * present only if the use of a custom picture format is + * signalled in PLUSPTYPE and UFEP is '001'. When present, CPFMT consists of: + * Bits 1-4 Pixel Aspect Ratio Code: A 4-bit index to the PAR value in Table 5. For + * extended PAR, the exact pixel aspect ratio shall be specified in EPAR + * (see 5.1.6); + * Bits 5-13 Picture Width Indication: Range [0, ... , 511]; Number of pixels per + * line = (PWI + 1) * 4; + * Bit 14 Equal to "1" to prevent start code emulation; + * Bits 15-23 Picture Height Indication: Range [1, ... , 288]; Number of lines = PHI * 4. + */ + /* 5.1.6 Extended Pixel Aspect Ratio (EPAR) (16 bits) + * A fixed length codeword of 16 bits that is present only if CPFMT is present and extended PAR is + * indicated therein. When present, EPAR consists of: + * Bits 1-8 PAR Width: "0" is forbidden. The natural binary representation of the PAR + * width; + * Bits 9-16 PAR Height: "0" is forbidden. The natural binary representation of the PAR + * height. + */ + /* 5.1.7 Custom Picture Clock Frequency Code (CPCFC) (8 bits) + * A fixed length codeword of 8 bits that is present only if PLUSPTYPE is present and UFEP is 001 + * and a custom picture clock frequency is signalled in PLUSPTYPE. When present, CPCFC consists of: + * Bit 1 Clock Conversion Code: "0" indicates a clock conversion factor of 1000 and + * "1" indicates 1001; + * Bits 2-8 Clock Divisor: "0" is forbidden. The natural binary representation of the value + * of the clock divisor. + */ + /* 5.1.8 Extended Temporal Reference (ETR) (2 bits) + * A fixed length codeword of 2 bits which is present only if a custom picture clock frequency is in + * use (regardless of the value of UFEP). It is the two MSBs of the 10-bit number defined in 5.1.2. + */ + /* 5.1.9 Unlimited Unrestricted Motion Vectors Indicator (UUI) (Variable length) + * A variable length codeword of 1 or 2 bits that is present only if the optional Unrestricted Motion + * Vector mode is indicated in PLUSPTYPE and UFEP is 001. When UUI is present it indicates the + * effective limitation of the range of the motion vectors being used. + * UUI = "1" The motion vector range is limited according to Tables D.1 and D.2. + * UUI = "01" The motion vector range is not limited except by the picture size. + */ + /* + * 5.1.10 Slice Structured Submode bits (SSS) (2 bits) + * A fixed length codeword of 2 bits which is present only if the optional Slice Structured mode + * (see Annex K) is indicated in PLUSPTYPE and UFEP is 001. If the Slice Structured mode is in use + * but UFEP is not 001, the last values sent for SSS shall remain in effect. + * – Bit 1 Rectangular Slices, "0" indicates free-running slices, "1" indicates rectangular + * slices; + * – Bit 2 Arbitrary Slice Ordering, "0" indicates sequential order, "1" indicates arbitrary + * order. + * 5.1.11 Enhancement Layer Number (ELNUM) (4 bits) + * A fixed length codeword of 4 bits which is present only if the optional Temporal, SNR, and Spatial + * Scalability mode is in use (regardless of the value of UFEP). The particular enhancement layer is + * identified by an enhancement layer number, ELNUM. Picture correspondence between layers is + * achieved via the temporal reference. Picture size is either indicated within each enhancement layer + * using the existing source format fields or is inferred by the relationship to the reference layer. The + * first enhancement layer above the base layer is designated as Enhancement Layer Number 2, and + * the base layer has number 1. + * 5.1.12 Reference Layer Number (RLNUM) (4 bits) + * A fixed length codeword of 4 bits which is present only if the optional Temporal, SNR, and Spatial + * Scalability mode is in use (see Annex O) and UFEP is 001. The layer number for the pictures used + * as reference anchors is identified by a Reference Layer Number (RLNUM). Time correspondence + * between layers is achieved via the temporal reference. + * Note that for B-pictures in an enhancement layer having temporally surrounding EI- or EP-pictures + * which are present in the same enhancement layer, RLNUM shall be equal to ELNUM + * (see Annex O). + * 5.1.13 Reference Picture Selection Mode Flags (RPSMF) (3 bits) + * A fixed length codeword of 3 bits that is present only if the Reference Picture Selection mode is in + * use and UFEP is 001. When present, RPSMF indicates which type of back-channel messages are + * needed by the encoder. If the Reference Picture Selection mode is in use but RPSMF is not present, + * the last value of RPSMF that was sent shall remain in effect. + * – 100: neither ACK nor NACK signals needed; + * – 101: need ACK signals to be returned; + * – 110: need NACK signals to be returned; + * – 111: need both ACK and NACK signals to be returned; + * – 000-011: Reserved. + * 5.1.14 Temporal Reference for Prediction Indication (TRPI) (1 bit) + * A fixed length codeword of 1 bit that is present only if the optional Reference Picture Selection + * mode is in use (regardless of the value of UFEP). When present, TRPI indicates the presence of the + * following TRP field: + * – 0: TRP field is not present; + * – 1: TRP field is present. + * TRPI shall be 0 whenever the picture header indicates an I- or EI-picture. + * 5.1.15 Temporal Reference for Prediction (TRP) (10 bits) + * When present (as indicated in TRPI), TRP indicates the Temporal Reference which is used for + * prediction of the encoding, except for in the case of B-pictures. For B-pictures, the picture having + * the temporal reference TRP is used for the prediction in the forward direction. (Prediction in the + * reverse-temporal direction always uses the immediately temporally subsequent picture.) TRP is a + * ten-bit number. If a custom picture clock frequency was not in use for the reference picture, the two + * MSBs of TRP are zero and the LSBs contain the eight-bit TR found in the picture header of the + * reference picture. If a custom picture clock frequency was in use for the reference picture, TRP is a + * ten-bit number consisting of the concatenation of ETR and TR from the reference picture header. + * When TRP is not present, the most recent temporally previous anchor picture shall be used for + * prediction, as when not in the Reference Picture Selection mode. TRP is valid until the next PSC, + * GSC, or SSC. + * 5.1.16 Back-Channel message Indication (BCI) (Variable length) + * A variable length field of one or two bits that is present only if the optional Reference Picture + * Selection mode is in use. When set to "1", this signals the presence of the following optional video + * Back-Channel Message (BCM) field. "01" indicates the absence or the end of the video backchannel + * message field. Combinations of BCM and BCI may not be present, and may be repeated + * when present. BCI shall be set to "01" if the videomux submode of the optional Reference Picture + * Selection mode is not in use. + * 5.1.17 Back-Channel Message (BCM) (Variable length) + * The Back-Channel message with syntax as specified in N.4.2, which is present only if the preceding + * BCI field is present and is set to "1". + * 5.1.18 Reference Picture Resampling Parameters (RPRP) (Variable length) + * A variable length field that is present only if the optional Reference Picture Resampling mode bit is + * set in PLUSPTYPE. This field carries the parameters of the Reference Picture Resampling mode + * (see Annex P). Note that the Reference Picture Resampling mode can also be invoked implicitly by + * the occurrence of a picture header for an INTER coded picture having a picture size which differs + * from that of the previous encoded picture, in which case the RPRP field is not present and the + * Reference Picture Resampling mode bit is not set. + */ + return offset_in_bits>>3; } /* 5.1.19 Quantizer Information (PQUANT) (5 bits) */ h263_proto_tree_add_bits( tree, hf_h263_pquant, tvb, offset_in_bits, 5, NULL); offset_in_bits = offset_in_bits +5; if (source_format != H263_PLUSPTYPE){ - h263_proto_tree_add_bits( tree, hf_h263_cpm, tvb, offset_in_bits, 1, NULL); + h263_proto_tree_add_bits( tree, hf_h263_cpm, tvb, offset_in_bits, 1, &cpm); offset_in_bits++; - h263_proto_tree_add_bits( tree, hf_h263_psbi, tvb, offset_in_bits, 2, NULL); - offset_in_bits = offset_in_bits +2; + /* 5.1.21 Picture Sub-Bitstream Indicator (PSBI) (2 bits) + * only present if Continuous Presence Multipoint and Video + * Multiplex mode is indicated by CPM. + */ + if(cpm==1){ + h263_proto_tree_add_bits( tree, hf_h263_psbi, tvb, offset_in_bits, 2, NULL); + offset_in_bits = offset_in_bits +2; + } } + /* 5.1.22 Temporal Reference for B-pictures in PB-frames (TRB) (3/5 bits) + * TRB is present if PTYPE or PLUSPTYPE indicates "PB-frame" or "Improved PB-frame" + * It is 3 bits long for standard CIF picture clock frequency and is + * extended to 5 bits when a custom picture clock frequency is in use. + */ + /* TODO Add the rest of the fields */ return offset_in_bits>>3; |