avcodec/cljrenc: Don't use too big buffers, don't copy them, set CAP_DR1

Up until now, the cljr encoder used buffers that were too big by a
factor of eight (probably bit/byte confusion). This has been fixed.
And because the needed buffer size can be easily calculated in advance,
one can avoid the implicit use of an intermediate buffer and can even
allow user-supplied buffers.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/cljrenc.c

@@ -28,6 +28,7 @@
 #include "libavutil/opt.h"
 
 #include "avcodec.h"
+#include "encode.h"
 #include "internal.h"
 #include "put_bits.h"
 
@@ -56,7 +57,8 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
          return AVERROR_EXPERIMENTAL;
     }
 
-    if ((ret = ff_alloc_packet2(avctx, pkt, 32*avctx->height*avctx->width/4, 0)) < 0)
+    ret = ff_get_encode_buffer(avctx, pkt, 4 * avctx->height * ((avctx->width + 3) / 4), 0);
+    if (ret < 0)
         return ret;
 
     init_put_bits(&pb, pkt->data, pkt->size);
@@ -89,7 +91,6 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
 
     flush_put_bits(&pb);
 
-    pkt->size   = put_bytes_output(&pb);
     pkt->flags |= AV_PKT_FLAG_KEY;
     *got_packet = 1;
     return 0;
@@ -114,6 +115,7 @@ const AVCodec ff_cljr_encoder = {
     .long_name      = NULL_IF_CONFIG_SMALL("Cirrus Logic AccuPak"),
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_CLJR,
+    .capabilities   = AV_CODEC_CAP_DR1,
     .priv_data_size = sizeof(CLJRContext),
     .encode2        = encode_frame,
     .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_YUV411P,