AviWriter.cc

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// Code based on DOSBox-0.65
 
#include "AviWriter.hh"
 
#include "FileOperations.hh"
#include "MSXException.hh"
#include "Version.hh"
 
#include "cstdiop.hh" // for snprintf
#include "endian.hh"
#include "narrow.hh"
#include "ranges.hh"
#include "small_buffer.hh"
#include "stl.hh"
#include "zstring_view.hh"
 
#include <array>
#include <cassert>
#include <cstring>
#include <ctime>
#include <limits>
 
namespace openmsx {
 
static constexpr unsigned AVI_HEADER_SIZE = 500;
 
AviWriter::AviWriter(const Filename& filename, unsigned width_,
                     unsigned height_, unsigned channels_, unsigned freq_)
        : file(filename, "wb")
        , codec(width_, height_)
        , width(width_)
        , height(height_)
        , channels(channels_)
        , audioRate(freq_)
{
        std::array<uint8_t, AVI_HEADER_SIZE> dummy = {};
        file.write(dummy);
 
        index.resize(2);
}
 
AviWriter::~AviWriter()
{
        if (written == 0) {
                // no data written yet (a recording less than one video frame)
                std::string filename = file.getURL();
                file.close(); // close file (needed for windows?)
                FileOperations::unlink(filename);
                return;
        }
        assert(fps != 0.0f); // a decent fps should have been set
 
        // Possible cleanup: use structs for the different headers, that
        // also allows to use the aligned versions of the Endian routines.
        std::array<uint8_t, AVI_HEADER_SIZE> avi_header = {};
        unsigned header_pos = 0;
 
        auto AVIOUT4 = [&](std::string_view s) {
                assert(s.size() == 4);
                ranges::copy(s, subspan(avi_header, header_pos));
                header_pos += 4;
        };
        auto AVIOUTw = [&](uint16_t w) {
                Endian::write_UA_L16(&avi_header[header_pos], w);
                header_pos += sizeof(w);
        };
        auto AVIOUTd = [&](uint32_t d) {
                Endian::write_UA_L32(&avi_header[header_pos], d);
                header_pos += sizeof(d);
        };
        auto AVIOUTs = [&](zstring_view s) {
                auto len1 = s.size() + 1; // +1 for zero-terminator
                ranges::copy(std::span{s.data(), len1}, subspan(avi_header, header_pos));
                header_pos += narrow<unsigned>((len1 + 1) & ~1); // round-up to even
        };
 
        bool hasAudio = audioRate != 0;
 
        // write avi header
        AVIOUT4("RIFF");                    // Riff header
        AVIOUTd(AVI_HEADER_SIZE + written - 8 + unsigned(index.size() * sizeof(Endian::L32)));
        AVIOUT4("AVI ");
        AVIOUT4("LIST");                    // List header
        auto main_list = header_pos;
        AVIOUTd(0);                         // size of list, filled in later
        AVIOUT4("hdrl");
 
        AVIOUT4("avih");
        AVIOUTd(56);                        // # of bytes to follow
        AVIOUTd(uint32_t(1000000 / fps));   // Microseconds per frame
        AVIOUTd(0);
        AVIOUTd(0);                         // PaddingGranularity (whatever that might be)
        AVIOUTd(0x110);                     // Flags,0x10 has index, 0x100 interleaved
        AVIOUTd(frames);                    // TotalFrames
        AVIOUTd(0);                         // InitialFrames
        AVIOUTd(hasAudio? 2 : 1);           // Stream count
        AVIOUTd(0);                         // SuggestedBufferSize
        AVIOUTd(width);                     // Width
        AVIOUTd(height);                    // Height
        AVIOUTd(0);                         // TimeScale:  Unit used to measure time
        AVIOUTd(0);                         // DataRate:   Data rate of playback
        AVIOUTd(0);                         // StartTime:  Starting time of AVI data
        AVIOUTd(0);                         // DataLength: Size of AVI data chunk
 
        // Video stream list
        AVIOUT4("LIST");
        AVIOUTd(4 + 8 + 56 + 8 + 40);       // Size of the list
        AVIOUT4("strl");
        // video stream header
        AVIOUT4("strh");
        AVIOUTd(56);                        // # of bytes to follow
        AVIOUT4("vids");                    // Type
        AVIOUT4(ZMBVEncoder::CODEC_4CC);    // Handler
        AVIOUTd(0);                         // Flags
        AVIOUTd(0);                         // Reserved, MS says: wPriority, wLanguage
        AVIOUTd(0);                         // InitialFrames
        AVIOUTd(1000000);                   // Scale
        AVIOUTd(uint32_t(1000000 * fps));   // Rate: Rate/Scale == samples/second
        AVIOUTd(0);                         // Start
        AVIOUTd(frames);                    // Length
        AVIOUTd(0);                         // SuggestedBufferSize
        AVIOUTd(uint32_t(~0));              // Quality
        AVIOUTd(0);                         // SampleSize
        AVIOUTd(0);                         // Frame
        AVIOUTd(0);                         // Frame
        // The video stream format
        AVIOUT4("strf");
        AVIOUTd(40);                        // # of bytes to follow
        AVIOUTd(40);                        // Size
        AVIOUTd(width);                     // Width
        AVIOUTd(height);                    // Height
        AVIOUTd(0);
        AVIOUT4(ZMBVEncoder::CODEC_4CC);    // Compression
        AVIOUTd(width * height * 4);        // SizeImage (in bytes?)
        AVIOUTd(0);                         // XPelsPerMeter
        AVIOUTd(0);                         // YPelsPerMeter
        AVIOUTd(0);                         // ClrUsed: Number of colors used
        AVIOUTd(0);                         // ClrImportant: Number of colors important
 
        if (hasAudio) {
                // 1 fragment is 1 (for mono) or 2 (for stereo) samples
                uint16_t bitsPerSample = 16;
                unsigned bytesPerSample = bitsPerSample / 8;
                unsigned bytesPerFragment = bytesPerSample * channels;
                unsigned bytesPerSecond = audioRate * bytesPerFragment;
                unsigned fragments = audioWritten / channels;
 
                // Audio stream list
                AVIOUT4("LIST");
                AVIOUTd(4 + 8 + 56 + 8 + 16);// Length of list in bytes
                AVIOUT4("strl");
                // The audio stream header
                AVIOUT4("strh");
                AVIOUTd(56);                // # of bytes to follow
                AVIOUT4("auds");
                AVIOUTd(0);                 // Format (Optionally)
                AVIOUTd(0);                 // Flags
                AVIOUTd(0);                 // Reserved, MS says: wPriority, wLanguage
                AVIOUTd(0);                 // InitialFrames
                // Rate/Scale should be number of samples per second!
                AVIOUTd(bytesPerFragment);  // Scale
                AVIOUTd(bytesPerSecond);    // Rate, actual rate is scale/rate
                AVIOUTd(0);                 // Start
                AVIOUTd(fragments);         // Length
                AVIOUTd(0);                 // SuggestedBufferSize
                AVIOUTd(unsigned(~0));      // Quality
                AVIOUTd(bytesPerFragment);  // SampleSize (should be the same as BlockAlign)
                AVIOUTd(0);                 // Frame
                AVIOUTd(0);                 // Frame
                // The audio stream format
                AVIOUT4("strf");
                AVIOUTd(16);                // # of bytes to follow
                AVIOUTw(1);                 // Format, WAVE_ZMBV_FORMAT_PCM
                AVIOUTw(narrow<uint16_t>(channels)); // Number of channels
                AVIOUTd(audioRate);         // SamplesPerSec
                AVIOUTd(bytesPerSecond);    // AvgBytesPerSec
                AVIOUTw(narrow<uint16_t>(bytesPerFragment)); // BlockAlign: for PCM: nChannels * BitsPerSample / 8
                AVIOUTw(bitsPerSample);     // BitsPerSample
        }
 
        std::string versionStr = Version::full();
 
        // The standard snprintf() function does always zero-terminate the
        // output it writes. Though windows doesn't have a snprintf() function,
        // instead we #define snprintf to _snprintf and the latter does NOT
        // properly zero-terminate. See also
        //   http://stackoverflow.com/questions/7706936/is-snprintf-always-null-terminating
        //
        // A buffer size of 11 characters is large enough till the year 9999.
        // But the compiler doesn't understand calendars and warns that the
        // snprintf output could be truncated (e.g. because the year is
        // -2147483647). To silence this warning (and also to work around the
        // windows _snprintf stuff) we add some extra buffer space.
        constexpr size_t size = (4 + 1 + 2 + 1 + 2 + 1) + 22;
        std::array<char, size> dateStr;
        time_t t = time(nullptr);
        const struct tm* tm = localtime(&t);
        size_t dateLen = snprintf(dateStr.data(), sizeof(dateStr), "%04d-%02d-%02d", 1900 + tm->tm_year,
                                  tm->tm_mon + 1, tm->tm_mday);
        assert(dateLen < size);
 
        AVIOUT4("LIST");
        AVIOUTd(narrow<uint32_t>(
                        4 // list type
                        + (4 + 4 + ((versionStr.size() + 1 + 1) & ~1)) // 1st chunk
                        + (4 + 4 + ((dateLen + 1 + 1) & ~1)) // 2nd chunk
                )); // size of the list
        AVIOUT4("INFO");
        AVIOUT4("ISFT");
        AVIOUTd(unsigned(versionStr.size()) + 1); // # of bytes to follow
        AVIOUTs(versionStr);
        AVIOUT4("ICRD");
        AVIOUTd(unsigned(dateLen) + 1); // # of bytes to follow
        AVIOUTs(zstring_view{dateStr.data(), dateLen});
        // TODO: add artist (IART), comments (ICMT), name (INAM), etc.
        // use a loop over chunks (type + string) to create the above bytes in
        // a much nicer way
 
        // Finish stream list, i.e. put number of bytes in the list to proper pos
        auto nMain = header_pos - main_list - 4;
        auto nJunk = AVI_HEADER_SIZE - 8 - 12 - header_pos;
        assert(nJunk > 0); // increase AVI_HEADER_SIZE if this occurs
        AVIOUT4("JUNK");
        AVIOUTd(nJunk);
        // Fix the size of the main list
        header_pos = main_list;
        AVIOUTd(nMain);
        header_pos = AVI_HEADER_SIZE - 12;
 
        AVIOUT4("LIST");
        AVIOUTd(written + 4);               // Length of list in bytes
        AVIOUT4("movi");
 
        try {
                // First add the index table to the end
                unsigned idxSize = unsigned(index.size()) * sizeof(Endian::L32);
                index[0] = ('i' << 0) | ('d' << 8) | ('x' << 16) | ('1' << 24);
                index[1] = idxSize - 8;
                file.write(std::span{index});
                file.seek(0);
                file.write(avi_header);
        } catch (MSXException&) {
                // can't throw from destructor
        }
}
 
void AviWriter::addAviChunk(std::span<const char, 4> tag, std::span<const uint8_t> data, unsigned flags)
{
        struct {
                std::array<char, 4> t;
                Endian::L32 s;
        } chunk;
 
        auto size32 = narrow<uint32_t>(data.size());
 
        ranges::copy(tag, chunk.t);
        chunk.s = size32;
        file.write(std::span{&chunk, 1});
 
        file.write(data);
        unsigned pos = written + 4;
        written += size32 + 8;
        if (size32 & 1) {
                std::array<uint8_t, 1> padding = {0};
                file.write(padding);
                ++written;
        }
 
        size_t idxSize = index.size();
        index.resize(idxSize + 4);
        memcpy(&index[idxSize], tag.data(), tag.size());
        index[idxSize + 1] = flags;
        index[idxSize + 2] = pos;
        index[idxSize + 3] = size32;
}
 
void AviWriter::addFrame(const FrameSource* video, std::span<const int16_t> audio)
{
        bool keyFrame = (frames++ % 300 == 0);
        auto buffer = codec.compressFrame(keyFrame, video);
        addAviChunk(subspan<4>("00dc"), buffer, keyFrame ? 0x10 : 0x0);
 
        if (!audio.empty()) {
                assert((audio.size() % channels) == 0);
                assert(audioRate != 0);
                if constexpr (Endian::BIG) {
                        small_buffer<Endian::L16, 4096> buf(audio);
                        addAviChunk(subspan<4>("01wb"), as_byte_span(std::span{buf}), 0);
                } else {
                        addAviChunk(subspan<4>("01wb"), as_byte_span(audio), 0);
                }
                audioWritten += narrow<uint32_t>(audio.size());
        }
}
 
} // namespace openmsx