| 17 | } |
| 18 | |
| 19 | Mpeg1Info Mpeg1::parseMpeg1Info(fl::span<const fl::u8> data, fl::string* error_message) { |
| 20 | Mpeg1Info info; |
| 21 | |
| 22 | // Validate input data |
| 23 | if (data.empty()) { |
| 24 | if (error_message) { |
| 25 | *error_message = "Empty MPEG1 data"; |
| 26 | } |
| 27 | return info; // returns invalid info |
| 28 | } |
| 29 | |
| 30 | // Minimum size check - MPEG1 needs at least the pack header and system header |
| 31 | if (data.size() < 12) { |
| 32 | if (error_message) { |
| 33 | *error_message = "MPEG1 data too small"; |
| 34 | } |
| 35 | return info; |
| 36 | } |
| 37 | |
| 38 | // Check for MPEG1 start codes |
| 39 | // Look for Pack Start Code (0x000001BA) or System Start Code (0x000001BB) |
| 40 | bool foundMpegHeader = false; |
| 41 | fl::size headerOffset = 0; |
| 42 | |
| 43 | for (fl::size i = 0; i <= data.size() - 4; i++) { |
| 44 | if (data[i] == 0x00 && data[i + 1] == 0x00 && data[i + 2] == 0x01) { |
| 45 | if (data[i + 3] == 0xBA || data[i + 3] == 0xBB) { |
| 46 | foundMpegHeader = true; |
| 47 | headerOffset = i; |
| 48 | break; |
| 49 | } |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | if (!foundMpegHeader) { |
| 54 | if (error_message) { |
| 55 | *error_message = "Invalid MPEG1 stream - no valid start code found"; |
| 56 | } |
| 57 | return info; |
| 58 | } |
| 59 | |
| 60 | // For detailed parsing, we need to use the actual decoder to extract metadata |
| 61 | // Since MPEG1 headers are complex, we'll use a temporary decoder instance |
| 62 | Mpeg1Config tempConfig; |
| 63 | tempConfig.mode = Mpeg1Config::SingleFrame; |
| 64 | tempConfig.skipAudio = true; |
| 65 | |
| 66 | auto decoder = fl::make_shared<third_party::SoftwareMpeg1Decoder>(tempConfig); |
| 67 | auto stream = fl::make_shared<fl::memorybuf>(data.size()); |
| 68 | stream->write(data); |
| 69 | |
| 70 | if (decoder->begin(stream)) { |
| 71 | // Extract metadata using decoder methods |
| 72 | info.width = decoder->getWidth(); |
| 73 | info.height = decoder->getHeight(); |
| 74 | info.frameRate = decoder->getFrameRate(); |
| 75 | info.frameCount = decoder->getFrameCount(); |
| 76 | |