mp4: Decode qt minor verison as YYYY.MM description

wader · Jan 16, 2023 · f386a51 · f386a51
1 parent c2795a7
commit f386a51
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Showing 4 changed files with 15 additions and 5 deletions.
diff --git a/format/mp4/boxes.go b/format/mp4/boxes.go
@@ -361,8 +361,18 @@ func decodeBoxIrefEntry(ctx *decodeContext, d *decode.D) {
 }
 
 func decodeBoxFtyp(d *decode.D) {
-	d.FieldUTF8("major_brand", 4)
-	d.FieldU32("minor_version")
+	brand := d.FieldUTF8("major_brand", 4)
+	d.FieldU32("minor_version", scalar.UintFn(func(s scalar.Uint) (scalar.Uint, error) {
+		switch brand {
+		case "qt  ":
+			// https://developer.apple.com/library/archive/documentation/QuickTime/QTFF/QTFFChap1/qtff1.html#//apple_ref/doc/uid/TP40000939-CH203-BBCGDDDF
+			// "For QuickTime movie files, this takes the form of four binary-coded decimal values, indicating the century,
+			//  year, and month of the QuickTime File Format Specification, followed by a binary coded decimal zero. For example,
+			//  for the June 2004 minor version, this field is set to the BCD values 20 04 06 00."
+			s.Description = fmt.Sprintf("%.4d.%.2d", (s.Actual>>24)&0xff_ff, (s.Actual>>8)&0xff)
+		}
+		return s, nil
+	}))
 	numBrands := d.BitsLeft() / 8 / 4
 	var i int64
 	d.FieldArrayLoop("brands", func() bool { return i < numBrands }, func(d *decode.D) {

diff --git a/format/mp4/testdata/in24.fqtest b/format/mp4/testdata/in24.fqtest
@@ -6,7 +6,7 @@ $ fq dv in24.mp4
 0x000|00 00 00 14                                    |....            |      size: 20 0x0-0x3.7 (4)
 0x000|            66 74 79 70                        |    ftyp        |      type: "ftyp" (File type and compatibility) 0x4-0x7.7 (4)
 0x000|                        71 74 20 20            |        qt      |      major_brand: "qt  " 0x8-0xb.7 (4)
-0x000|                                    00 00 02 00|            ....|      minor_version: 512 0xc-0xf.7 (4)
+0x000|                                    00 00 02 00|            ....|      minor_version: 512 (0000.02) 0xc-0xf.7 (4)
      |                                               |                |      brands[0:1]: 0x10-0x13.7 (4)
 0x010|71 74 20 20                                    |qt              |        [0]: "qt" brand 0x10-0x13.7 (4)
      |                                               |                |    [1]{}: box 0x14-0x1b.7 (8)

diff --git a/format/mp4/testdata/lpcm.fqtest b/format/mp4/testdata/lpcm.fqtest
@@ -6,7 +6,7 @@ $ fq dv lpcm.mp4
 0x000|00 00 00 14                                    |....            |      size: 20 0x0-0x3.7 (4)
 0x000|            66 74 79 70                        |    ftyp        |      type: "ftyp" (File type and compatibility) 0x4-0x7.7 (4)
 0x000|                        71 74 20 20            |        qt      |      major_brand: "qt  " 0x8-0xb.7 (4)
-0x000|                                    00 00 02 00|            ....|      minor_version: 512 0xc-0xf.7 (4)
+0x000|                                    00 00 02 00|            ....|      minor_version: 512 (0000.02) 0xc-0xf.7 (4)
      |                                               |                |      brands[0:1]: 0x10-0x13.7 (4)
 0x010|71 74 20 20                                    |qt              |        [0]: "qt" brand 0x10-0x13.7 (4)
      |                                               |                |    [1]{}: box 0x14-0x1b.7 (8)

diff --git a/format/prores/testdata/prores_frame.fqtest b/format/prores/testdata/prores_frame.fqtest
@@ -6,7 +6,7 @@ $ fq -d mp4 dv prores_frame.mov
 0x0000|00 00 00 14                                    |....            |      size: 20 0x0-0x3.7 (4)
 0x0000|            66 74 79 70                        |    ftyp        |      type: "ftyp" (File type and compatibility) 0x4-0x7.7 (4)
 0x0000|                        71 74 20 20            |        qt      |      major_brand: "qt  " 0x8-0xb.7 (4)
-0x0000|                                    00 00 02 00|            ....|      minor_version: 512 0xc-0xf.7 (4)
+0x0000|                                    00 00 02 00|            ....|      minor_version: 512 (0000.02) 0xc-0xf.7 (4)
       |                                               |                |      brands[0:1]: 0x10-0x13.7 (4)
 0x0010|71 74 20 20                                    |qt              |        [0]: "qt" brand 0x10-0x13.7 (4)
       |                                               |                |    [1]{}: box 0x14-0x1b.7 (8)