/*

    makeiPhoneRefMovie.c

    cc -o makeiPhoneRefMovie -g makeiPhoneRefMovie.c

    Creates a special-purpose reference movie for iPhone.

    Copyright 2007. All rights reserved.

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the Apple Software without specific prior written permission from Apple.  Except as

expressly stated in this notice, no other rights or licenses, express or implied, are

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The Apple Software is provided by Apple on an "AS IS" basis.  APPLE MAKES NO WARRANTIES,

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*/

/****

    For information about reference movies see the following documentation:

    Ice Floe #15 Creating Alternate Movies

        http://developer.apple.com/quicktime/icefloe/dispatch015.html

    QuickTime File Format Specification - Reference Movies

        http://developer.apple.com/documentation/QuickTime/QTFF/QTFFChap2/chapter_3_section_7.html

    NOTE: iPhone 1.0 synthesises a fake Gestalt selector 'mobi' with bitfield value 0x00000001.

****/

#include <stdio.h>

#include <stdint.h>

#include <string.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <libkern/OSByteOrder.h>

struct Options {

    const char *desktopPath;

    const char *lowPath;

    const char *highPath;

};

// writeHeader and patchHeader are utility functions

// writeHeader writes the atom header returning the header offset for each atom being written

// patchHeader updates the atom size correctly after all the atom data has been written

static void writeHeader( FILE *outputFile, uint32_t atomType, off_t *headerOffset )

{

    uint32_t atomSize = 'patc';

    atomSize = OSSwapHostToBigInt32( atomSize );

    atomType = OSSwapHostToBigInt32( atomType );

    *headerOffset = ftello( outputFile );                 // ftello is identical to ftell but returns an off_t which can be a 64-bit type

    fwrite( &atomSize, sizeof(atomSize), 1, outputFile ); // will be patched later

    fwrite( &atomType, sizeof(atomType), 1, outputFile );

}

static void patchHeader( FILE *outputFile, off_t headerOffset )

{

    off_t saveOffset = ftello( outputFile );

    uint32_t atomSize = saveOffset - headerOffset;

    fseeko( outputFile, headerOffset, SEEK_SET );

    atomSize = OSSwapHostToBigInt32( atomSize );

    fwrite( &atomSize, sizeof(atomSize), 1, outputFile );

    fseeko( outputFile, saveOffset, SEEK_SET );

}

// write the data rate atom 'rmdr'

static void write_rdrf( FILE *outputFile, const char *path )

{

    off_t headerOffset;

    size_t pathSize = strlen( path ) + 1; // include NULL

    uint32_t flags = 0;

    uint32_t dataRefType = OSSwapHostToBigInt32( 'url ' );

    uint32_t dataRefSize = OSSwapHostToBigInt32( pathSize );

    writeHeader( outputFile, 'rdrf', &headerOffset );

    fwrite( &flags, sizeof(flags), 1, outputFile );

    fwrite( &dataRefType, sizeof(dataRefType), 1, outputFile );

    fwrite( &dataRefSize, sizeof(dataRefSize), 1, outputFile );

    fwrite( path, pathSize, 1, outputFile );

    patchHeader( outputFile, headerOffset );

}

// taken from MoviesFormat.h

enum {

    kDataRate288ModemRate         = 2800L,

    kDataRateLowRate              = 11200L,

    kDataRate1MbpsRate            = 100000L,

};

// write the data reference atom 'rdrf'

static void write_rmdr( FILE *outputFile, uint32_t dataRate )

{

    off_t headerOffset;

    uint32_t flags = 0;

    dataRate = OSSwapHostToBigInt32( dataRate );

    writeHeader( outputFile, 'rmdr', &headerOffset );

    fwrite( &flags, sizeof(flags), 1, outputFile );

    fwrite( &dataRate, sizeof(dataRate), 1, outputFile );

    patchHeader( outputFile, headerOffset );

}

// write the iPhone version check atom 'rmvc'

static void write_iPhone_rmvc( FILE *outputFile )

{

    off_t headerOffset;

    uint32_t flags = 0;

    uint32_t gestaltTag = OSSwapHostToBigInt32( 'mobi' );

    uint32_t val1 = OSSwapHostToBigInt32( 1 ); // bitflags is 1

    uint32_t val2 = OSSwapHostToBigInt32( 1 ); // bitmask is 1

    uint16_t checkType = OSSwapHostToBigInt16( 1 ); // type is mask

    writeHeader( outputFile, 'rmvc', &headerOffset );

    fwrite( &flags, sizeof(flags), 1, outputFile );

    fwrite( &gestaltTag, sizeof(gestaltTag), 1, outputFile );

    fwrite( &val1, sizeof(val1), 1, outputFile );

    fwrite( &val2, sizeof(val2), 1, outputFile );

    fwrite( &checkType, sizeof(checkType), 1, outputFile );

    patchHeader( outputFile, headerOffset );

}

enum {

    kNoRequirements = 0,

    kRequireiPhone = 1,

};

// for each reference, create the appropriate 'rmda'

// in each reference write a data reference atom 'rdrf' and a data rate atom 'rmdr'

// in the iPhone cases "kRequireiPhone" also write a version check atom 'rmvc'

static void write_rmda( FILE *outputFile, const char *path, int requirements, uint32_t dataRate )

{

    off_t headerOffset;

    writeHeader( outputFile, 'rmda', &headerOffset );

    write_rdrf( outputFile, path );

    write_rmdr( outputFile, dataRate );

    if( requirements & kRequireiPhone )

        write_iPhone_rmvc( outputFile );

    patchHeader( outputFile, headerOffset );

}

// write the 'rmra' and add each Reference Movie Descriptor Atom 'rmda'

// NOTE: The order DOES matter here  -- the last one that passes all of

// its checks (data rate, version check) wins. Since we can only describe

// "data rate >= x" and "we are on iPhone" and not the opposites of those checks,

// there's only one order to put the 'rmra' atoms in such that they can all be effective.

static void write_rmra( FILE *outputFile, struct Options *options )

{

    off_t headerOffset;

    writeHeader( outputFile, 'rmra', &headerOffset );

    write_rmda( outputFile, options->desktopPath, kNoRequirements, kDataRate288ModemRate );

    write_rmda( outputFile, options->lowPath,     kRequireiPhone,  kDataRateLowRate );

    write_rmda( outputFile, options->highPath,    kRequireiPhone,  kDataRate1MbpsRate );

    patchHeader( outputFile, headerOffset );

}

// create the reference movie - write the 'moov' header and populate the 'rmra' atom

static void write_moov( FILE *outputFile, struct Options *options )

{

    off_t headerOffset;

    writeHeader( outputFile, 'moov', &headerOffset );

    write_rmra( outputFile, options );

    patchHeader( outputFile, headerOffset );

}

// display the usage message

static void usage( const char *argv0 )

{

    fprintf( stderr, "usage: %s foo-low.3gp foo-high.m4v foo-desktop.mov foo-ref.mov\n", argv0 );

    fprintf( stderr, "\tcreates foo-ref.mov with a special-purpose iPhone ref movie\n" );

    fprintf( stderr, "\tthe other files need not exist; they're just embedded as URLs\n" );

    exit(1);

}

int main(int argc, const char **argv)

{

    const char *argv0 = argv[0];

    struct Options options = {0};

    const char *outputPath;

    FILE *outputFile = NULL;

    struct stat sb;

    if( argc != 5 )

        usage( argv0 );

    // grab the paths to the sources and destination

    options.lowPath = argv[1];

    options.highPath = argv[2];

    options.desktopPath = argv[3];

    outputPath = argv[4];

    if( 0 == stat( outputPath, &sb ) ) {

        fprintf( stderr, "%s: file exists\n", outputPath );

        return 1;

    }

    outputFile = fopen( outputPath, "w" );

    printf( "writing an iPhone ref movie to %s with:\n", outputPath );

    printf( "  on iPhone, low bitrate    => %s\n", options.lowPath );

    printf( "  on iPhone, higher bitrate => %s\n", options.highPath );

    printf( "  otherwise                 => %s\n", options.desktopPath );

    // do the work

    write_moov( outputFile, &options );

    fclose( outputFile );

    return 0;

}