[Ffmpeg-devel] [PATCH] ported SGI decoder to the new API

[Xiaohui Sun]

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Hi,

Michael Niedermayer wrote:
> Hi
> 
> On Tue, Mar 27, 2007 at 03:34:39PM +0800, Xiaohui Sun wrote:
>> Hi,
>>      I have updated the path, Thank you again for your suggestions about
>> my code.
>>
>> the new patch
>> --  ported SGI encoder
>> --  seperate encoder/decoder into two files
>> --  fixed some problems of the previous code
> 
> [...]
> 
>> +        for (y = s->height - 1; y >= 0; y--) {
>> +            dest_row = ptr + (y * s->linesize);
>> +            for (x = s->width; x > 0; x--) {
>> +                dest_row[chan_offset] = bytestream_get_byte(&buf);
>> +                dest_row += s->depth;
>> +            }
>> +        }
> 
> sequential writes with random reads are faster then sequential reads with
> random writes
> 

I should alloc an separate buffer, read the data in and use memcpy() to
do a sequential writes?

[...]
> [...]
>> +static int encode_init(AVCodecContext *avctx){
>> +    SgiContext *s = avctx->priv_data;
>> +
>> +    avcodec_get_frame_defaults((AVFrame*)&s->picture);
>> +    avctx->coded_frame = (AVFrame*)&s->picture;
>> +
>> +    return 0;
>> +}
> 
> code duplication
> 
> 

the structure of the avctx->priv_data is not the same in encode and decode



> [...]
>> +static int encode_frame(AVCodecContext *avctx, unsigned char *buf, 
>> +			int buf_size, void *data){
>> +    SgiContext *s = avctx->priv_data;
>> +    AVFrame * const p = &s->picture;
>> +    long *offsettab, *lengthtab;
>> +    int i, y, z;
>> +    int tablesize, chan_offset;
>> +    uint8_t *srcrow;
>> +    unsigned int width, height, depth, dimension;
>> +    unsigned int n_bytes;
>> +    unsigned char *buf0 = buf;
>> +
> 
> there are no checks for buf_size being large enough
> 
> 

we can not get the encoded image size before we actually encode it


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