移动并修复手机iOS上录制的视频的moov原子 [英] Move and fix moov atom of video recorded on phone iOS

问题描述

问题是如何找到并移动记录在iOS设备上的.mov文件的moov原子，以便您可以通过http传输它。有一种方法可以做到这一点，但需要将其导出到文件，理论上这使您可以复制整个文件，然后您就可以将其流式传输。

The question is how do you find and move the moov atom of a .mov file that is recorded on an iOS device so you can stream it over http. There is one way to do it but that requires to export it to file which in theory makes you copy the entire file over and then you would be able to stream it.

还有其他办法吗？

推荐答案

这里是我编辑和编写的方法的代码，用于与iOS一起查找然后将moov原子写入特定位置，因此在您拥有视频文件的这两部分之后，您只需要访问视频文件的字节FTYP原子结束的地方（看看标记为start_offset和last_offset的变量）并且将发生流式传输。

Here is the code to a method I edited and wrote to work with iOS to find and then write the moov atom to specific location so then right after you have these two parts of the video file you just need to access the bytes of the video file from where the FTYP atom ends(take a look at the variables marked as start_offset and last_offset) and the streaming will occur.

- (NSString *)fixForFastPlayback:(char*)dest:(ALAsset*)selected
{
    FILE *infile  = NULL;
    FILE *outfile = NULL;
    uint32_t atom_type = 0;
    uint64_t atom_size = 0;
    uint64_t atom_offset = 0;
    uint64_t last_offset;
    uint64_t moov_atom_size;
    uint64_t ftyp_atom_size = 0;
    uint64_t i, j;
    uint32_t offset_count;
    uint64_t current_offset;
    uint64_t start_offset = 0;

    ALAssetRepresentation * rep = [[selected defaultRepresentation] retain];

    int bufferSize = 8192; // or use 8192 size as read from other posts

    int read = 0;
    NSError * err = nil;

    uint8_t * buffer = calloc(bufferSize, sizeof(*buffer));
    uint8_t * ftyp_atom;
    /* traverse through the atoms in the file to make sure that 'moov' is
     * at the end */
    int asset_offset = 0;
    while (asset_offset < [rep size])
    {

        read = [rep getBytes:buffer
                  fromOffset:asset_offset
                      length:ATOM_PREAMBLE_SIZE
                       error:&err];

        asset_offset += read;

        if (err != nil)
        {
            NSLog(@"Error: %@ %@", err, [err userInfo]);
        }


        atom_size = (uint32_t)BE_32(&buffer[0]);
        atom_type = BE_32(&buffer[4]);

        /* keep ftyp atom */
        if (atom_type == FTYP_ATOM) //no idea what an atom is, maybe a header or some sort of meta data or a file marker
        {

            ftyp_atom_size = atom_size;
            ftyp_atom = calloc(ftyp_atom_size, sizeof(*buffer));

            if (!ftyp_atom)
            {
                printf ("could not allocate %"PRIu64" byte for ftyp atom\n",
                        atom_size);

            }


            asset_offset -= ATOM_PREAMBLE_SIZE;

            read = [rep getBytes:ftyp_atom
                      fromOffset:asset_offset
                          length:ftyp_atom_size
                           error:&err];

            asset_offset += read;

            start_offset = asset_offset;

        }
        else
        {

            asset_offset += (atom_size - ATOM_PREAMBLE_SIZE);

        }

        printf("%c%c%c%c %10"PRIu64" %"PRIu64"\n",
               (atom_type >> 24) & 255,
               (atom_type >> 16) & 255,
               (atom_type >>  8) & 255,
               (atom_type >>  0) & 255,
               atom_offset,
               atom_size);
        if ((atom_type != FREE_ATOM) &&
            (atom_type != JUNK_ATOM) &&
            (atom_type != MDAT_ATOM) &&
            (atom_type != MOOV_ATOM) &&
            (atom_type != PNOT_ATOM) &&
            (atom_type != SKIP_ATOM) &&
            (atom_type != WIDE_ATOM) &&
            (atom_type != PICT_ATOM) &&
            (atom_type != UUID_ATOM) &&
            (atom_type != FTYP_ATOM))
        {
            printf ("encountered non-QT top-level atom (is this a Quicktime file?)\n");
            break;
        }
        atom_offset += atom_size;

        /* The atom header is 8 (or 16 bytes), if the atom size (which
         * includes these 8 or 16 bytes) is less than that, we won't be
         * able to continue scanning sensibly after this atom, so break. */
        if (atom_size < 8)
            break;
    }

    if (atom_type != MOOV_ATOM)
    {
        printf ("last atom in file was not a moov atom\n");
        free(ftyp_atom);
        fclose(infile);
        return 0;
    }

    asset_offset = [rep size];
    asset_offset -= atom_size;
    last_offset = asset_offset;



    moov_atom_size = atom_size;
    uint8_t * moov_atom = calloc(moov_atom_size, sizeof(*buffer));

    if (!moov_atom)
    {
        printf ("could not allocate %"PRIu64" byte for moov atom\n",
                atom_size);

    }
    read = [rep getBytes:moov_atom
              fromOffset:asset_offset
                  length:moov_atom_size
                   error:&err];

    asset_offset += read;

    /* this utility does not support compressed atoms yet, so disqualify
     * files with compressed QT atoms */
    if (BE_32(&moov_atom[12]) == CMOV_ATOM)
    {
        printf ("this utility does not support compressed moov atoms yet\n");

    }

    /* crawl through the moov chunk in search of stco or co64 atoms */
    for (i = 4; i < moov_atom_size - 4; i++)
    {
        atom_type = BE_32(&moov_atom[i]);

        if (atom_type == STCO_ATOM)
        {
            printf (" patching stco atom...\n");
            atom_size = BE_32(&moov_atom[i - 4]);
            if (i + atom_size - 4 > moov_atom_size)
            {
                printf (" bad atom size\n");

            }
            offset_count = BE_32(&moov_atom[i + 8]);
            for (j = 0; j < offset_count; j++)
            {
                current_offset = BE_32(&moov_atom[i + 12 + j * 4]);
                current_offset += moov_atom_size;
                moov_atom[i + 12 + j * 4 + 0] = (current_offset >> 24) & 0xFF;
                moov_atom[i + 12 + j * 4 + 1] = (current_offset >> 16) & 0xFF;
                moov_atom[i + 12 + j * 4 + 2] = (current_offset >>  8) & 0xFF;
                moov_atom[i + 12 + j * 4 + 3] = (current_offset >>  0) & 0xFF;
            }
            i += atom_size - 4;
        }
        else if (atom_type == CO64_ATOM)
        {

            printf (" patching co64 atom...\n");
            atom_size = BE_32(&moov_atom[i - 4]);
            if (i + atom_size - 4 > moov_atom_size)
            {
                printf (" bad atom size\n");

            }
            offset_count = BE_32(&moov_atom[i + 8]);
            for (j = 0; j < offset_count; j++)
            {
                current_offset = BE_64(&moov_atom[i + 12 + j * 8]);
                current_offset += moov_atom_size;
                moov_atom[i + 12 + j * 8 + 0] = (current_offset >> 56) & 0xFF;
                moov_atom[i + 12 + j * 8 + 1] = (current_offset >> 48) & 0xFF;
                moov_atom[i + 12 + j * 8 + 2] = (current_offset >> 40) & 0xFF;
                moov_atom[i + 12 + j * 8 + 3] = (current_offset >> 32) & 0xFF;
                moov_atom[i + 12 + j * 8 + 4] = (current_offset >> 24) & 0xFF;
                moov_atom[i + 12 + j * 8 + 5] = (current_offset >> 16) & 0xFF;
                moov_atom[i + 12 + j * 8 + 6] = (current_offset >>  8) & 0xFF;
                moov_atom[i + 12 + j * 8 + 7] = (current_offset >>  0) & 0xFF;
            }
            i += atom_size - 4;
        }
    }

    outfile = fopen(dest, "wb");
    NSLog(@"%llu",last_offset);

    //global variables to be used when returning the actual data
    start_offset_not_c = start_offset;
    last_offset_not_c = last_offset;

    if (ftyp_atom_size > 0)
    {
        printf ("writing ftyp atom...\n");
        if (fwrite(ftyp_atom, ftyp_atom_size, 1, outfile) != 1)
        {
            perror(dest);
        }
    }

    printf ("writing moov atom...\n");
    if (fwrite(moov_atom, moov_atom_size, 1, outfile) != 1)
    {
        perror(dest);
    }

    fclose(outfile);
    free(ftyp_atom);
    free(moov_atom);
    ftyp_atom = NULL;
    moov_atom = NULL;

    return [NSString stringWithCString:dest encoding:NSStringEncodingConversionAllowLossy];
}

享受！

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