[FFmpeg-devel] [PATCH] libopenjpeg wrapper for jpeg2k decoding

[Jai Menon]

Hi,

2009/1/29 Michael Niedermayer <michaelni at gmx.at>:
> On Thu, Jan 29, 2009 at 11:35:31AM +0530, Jai Menon wrote:

[...]

>> +static int libopenjpeg_decode_frame(AVCodecContext *avctx,
>> +                                    void *data, int *data_size,
>> +                                    const uint8_t *buf, int buf_size)
>> +{
>> +    LibOpenJPEGContext *ctx = avctx->priv_data;
>> +    AVPicture *picture = data;
>> +    opj_dinfo_t *dec = NULL;
>> +    opj_cio_t *stream = NULL;
>> +    opj_image_t *image = NULL;
>> +    int width, height, has_alpha = 0, ret = -1;
>> +    int x, y, index;
>> +    int picture_size;
>> +    uint8_t *img_ptr;
>> +    float scale;
>> +
>> +    *data_size = 0;
>> +
>> +    // Check if input is a raw jpeg2k codestream or in jp2 wrapping
>> +    if((AV_RB32(buf) == 12) &&
>> +       (AV_RB32(buf + 4) == JP2_SIG_TYPE) &&
>> +       (AV_RB32(buf + 8) == JP2_SIG_VALUE)) {
>> +        dec = opj_create_decompress(CODEC_JP2);
>> +    }
>> +    else dec = opj_create_decompress(CODEC_J2K);
>
> dec is written to twice with no read in between, this applies to more vars

I didn't quite get what this implies, other than that the
initialization at the top can be removed.

> [...]
>> +    picture_size = avpicture_get_size(avctx->pix_fmt, avctx->width, avctx->height);
>> +    if(!ctx->img_buf) {
>> +        ctx->img_buf = av_mallocz(picture_size);
>> +        if(!ctx->img_buf) {
>> +            av_log(avctx, AV_LOG_ERROR, "Couldn't allocate image buffer.\n");
>> +            goto done;
>> +        }
>> +    }
>> +    img_ptr = ctx->img_buf;
>> +    picture->data[0] = ctx->img_buf;
>> +    scale = 255.0f / (float)((1 << image->comps[0].prec) - 1);
>> +    for(y = 0; y < height; y++) {
>> +        index = y*width;
>> +        for(x = 0; x < width; x++, index++) {
>> +            *img_ptr++ = image->comps[0].data[index] * scale;
>> +            if(image->numcomps > 2 && check_image_attributes(image)) {
>> +                *img_ptr++ = image->comps[1].data[index] * scale;
>> +                *img_ptr++ = image->comps[2].data[index] * scale;
>> +                if(has_alpha)
>> +                    *img_ptr++ = image->comps[3].data[index] * scale;
>> +            }
>> +        }
>> +    }
>
> sec hole when width/height changes

The assumption here was that width/height wouldn't change. Allocating
the buffer
for each frame was too slow. I could change it though, I mostly care only about
the soc code :-)

[...]

-- 
Regards,

Jai