[Ffmpeg-devel] [PATCH] BMP encoder
Michel Bardiaux
mbardiaux
Mon Oct 30 17:36:24 CET 2006
Michael Niedermayer wrote:
> Hi
>
> On Mon, Oct 30, 2006 at 04:05:39PM +0100, Michel Bardiaux wrote:
>> Currently, only straight RGB.
> [...]
>> + init_put_bits(&s->pb, buf, buf_size);
>> + // STRUCTURE.field refer to the MSVC documentation
>> + // BITMAPFILEHEADER.bfType
>> + put_bits(&s->pb, 8, 'B');
>> + put_bits(&s->pb, 8, 'M');
>> + // BITMAPFILEHEADER.bfSize
>> + write32(&s->pb, n_bytes);
>> + // BITMAPFILEHEADER.bfReserved1
>> + write16(&s->pb, 0);
>> + // BITMAPFILEHEADER.bfReserved2
>> + write16(&s->pb, 0);
>> + // BITMAPFILEHEADER.bfOffBits
>> + write32(&s->pb, 14 /* BITMAPFILEHEADER */ + 40);
>> + // BITMAPINFOHEADER.biSize
>> + write32(&s->pb, 40);
>> + // BITMAPINFOHEADER.biWidth
>> + write32(&s->pb, avctx->width);
>> + // BITMAPINFOHEADER.biHeight
>> + write32(&s->pb, avctx->height);
>> + // BITMAPINFOHEADER.biPlanes
>> + write16(&s->pb, 1);
>> + // BITMAPINFOHEADER.biBitCount
>> + write16(&s->pb, 24);
>> + // BITMAPINFOHEADER.biCompression
>> + write32(&s->pb, BMP_RGB);
>> + // BITMAPINFOHEADER.biSizeImage
>> + write32(&s->pb, n_bytes_image);
>> + // BITMAPINFOHEADER.biXPelsPerMeter
>> + write32(&s->pb, 0);
>> + // BITMAPINFOHEADER.biYPelsPerMeter
>> + write32(&s->pb, 0);
>> + // BITMAPINFOHEADER.biClrUsed
>> + write32(&s->pb, 0);
>> + // BITMAPINFOHEADER.biClrImportant
>
> see put_bmp_header()
Right, I have recoded the wheel. But I cant use it unchanged; first
because it is in libavformat, second because it seems intimately linked
to asf and avi.
I see 2 ways: recode it in the bmp encoder; or define our own bitmap
structures to separate setting the values and writing them. For the time
being I will take the 1st way.
>
>
>> + write32(&s->pb, 0);
>> + // BMP files are bottom-to-top
>> + ptr = p->data[0] + (avctx->height - 1) * p->linesize[0];
>> + linesize = -p->linesize[0];
>> + for(i = 0; i < avctx->height; i++){
>> + uint8_t *src = ptr;
>> + int n = 0;
>> + for(j=0;j<avctx->width;j++) {
>> + put_bits(&s->pb, 8, src[0]);
>> + put_bits(&s->pb, 8, src[1]);
>> + put_bits(&s->pb, 8, src[2]);
>
> using the bitstream reader for a purely byte based format is unacceptable
> (reason is that its several times slower and more complex)
Right. Will change to use put_le16 etc. But see above.
>
>
>> + src += 3;
>> + n += 3;
>> + }
>> + for(;n<n_bytes_per_row;n++) put_bits(&s->pb, 8, 0);
>> + ptr += linesize;
>> + }
>> + return n_bytes;
>> +}
>
> [...]
>
>> Index: libavcodec/amr.c
>> ===================================================================
>> --- libavcodec/amr.c (revision 6838)
>> +++ libavcodec/amr.c (working copy)
>> @@ -57,6 +57,8 @@
>>
>> #include "avcodec.h"
>>
>> +#if defined(CONFIG_AMR_NB) || defined(CONFIG_AMR_NB_FIXED)
>> +
>> #ifdef CONFIG_AMR_NB_FIXED
>>
>> #define MMS_IO
>> @@ -494,8 +496,6 @@
>>
>> #endif
>>
>> -#if defined(CONFIG_AMR_NB) || defined(CONFIG_AMR_NB_FIXED)
>> -
>> AVCodec amr_nb_decoder =
>> {
>> "amr_nb",
>
> huh? what is this?
An unrelated work that indeed has nothing to do in that patch.
>
> [...]
>
--
Michel Bardiaux
R&D Director
T +32 [0] 2 790 29 41
F +32 [0] 2 790 29 02
E mailto:mbardiaux at mediaxim.be
Mediaxim NV/SA
Vorstlaan 191 Boulevard du Souverain
Brussel 1160 Bruxelles
http://www.mediaxim.com/
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