SubtitleEdit/subtitleedit · warning · Exception

Too many bytes for CCData!

Error message

Too many bytes for CCData!

What it means

Thrown by the CEA-708 CcDataSection constructor when the supplied byte array contains more than 16 caption-character pairs (i.e. bytes.Length > 32). Per ATSC A/53 the cc_data block in a picture user-data field holds at most 16 CC pairs per field; exceeding that means the input is malformed or the caller mis-parsed the count.

Source

Thrown at src/libse/Cea708/CcDataSection.cs:52

                {
                    Valid = (bytes[index + i * 3 + 2] & 0b00000100) > 0,
                    Type = bytes[index + i * 3 + 2] & 0b00000011,
                    Data1 = bytes[index + i * 3 + 3],
                    Data2 = bytes[index + i * 3 + 4]
                };
            }
        }

        public CcDataSection(int ccDataCount, byte[] bytes, int sequenceCount)
        {
            DataSection = 0x72;
            ProcessEmData = true;
            ProcessCcData = true;
            AdditionalData = true;

            if (bytes.Length / 2 > 16)
            {
                throw new Exception("Too many bytes for CCData!");
            }

            CcData = new CcData[ccDataCount];
            var bytesIndex = 0;
            var lastContent = true;
            for (int i = 0; i < ccDataCount; i++)
            {
                if (i == 0)
                {
                    CcData[i] = new CcData
                    {
                        Valid = true,
                        Type = 0,
                        Data1 = 0x80,
                        Data2 = 0x80,
                    };
                }
                else if (i == 1)

View on GitHub (pinned to 17a9f07487)

Solutions

1. Verify bytes.Length <= 32 and ccDataCount == bytes.Length/2 before constructing CcDataSection.
2. Split the incoming payload into <=32-byte cc_data chunks per picture before calling the constructor.
3. Clamp or truncate oversize buffers with a logged warning instead of throwing.
4. Regenerate the captions from a trusted source rather than editing raw bytes.

Example fix

// before
if (bytes.Length / 2 > 16)
{
    throw new Exception("Too many bytes for CCData!");
}

// after
const int MaxCcPairs = 16;
var usable = Math.Min(bytes.Length / 2, MaxCcPairs);
if (usable < bytes.Length / 2)
{
    Logger.Warn($"CcData truncated from {bytes.Length / 2} to {MaxCcPairs} pairs.");
}
// proceed using `usable` pairs

if (bytes == null || bytes.Length / 2 > 16 || bytes.Length % 2 != 0) throw new ArgumentException("cc_data must be <= 32 bytes and even length");

try { var section = new CcDataSection(count, bytes, seq); }
catch (Exception ex) when (ex.Message.Contains("CCData")) { /* split or drop packet */ }

When it happens

Trigger: Passing a raw bytes array larger than 32 to the CcDataSection(int, byte[], int) constructor; ccDataCount not matching bytes.Length/2; feeding concatenated cc_data sections from multiple frames as one.

Common situations: Hand-assembled caption packets; buggy upstream ATSC/SEI extractor that did not split cc_data by frame boundary; corrupted transport stream where the SEI payload length is wrong.

Related errors

• Unable to access bitmap pixel data.
• Color '{colorName}' not found in SKColors.
• Dvd language {code} not found!
• End of file reached before expected
• MXF KLV packet - lenght bytes > 8

AI-assisted analysis of SubtitleEdit/subtitleedit@17a9f07487 (2026-08-13). Data as JSON: /api/errors/e77191589a8edd83. Report an issue: GitHub.