avcodec/[e]ac3enc: Allow user-supplied buffers

The size of the output buffer is always known in advance and
the code has no alignment requirement (it uses mostly the PutBits API),
so allowing user-supplied buffers is trivial.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/ac3enc.c

@@ -38,6 +38,7 @@
 #include "libavutil/opt.h"
 #include "libavutil/thread.h"
 #include "avcodec.h"
+#include "encode.h"
 #include "internal.h"
 #include "me_cmp.h"
 #include "put_bits.h"
@@ -1760,7 +1761,7 @@ int ff_ac3_encode_frame_common_end(AVCodecContext *avctx, AVPacket *avpkt,
 
     ac3_quantize_mantissas(s);
 
-    ret = ff_alloc_packet2(avctx, avpkt, s->frame_size, s->frame_size);
+    ret = ff_get_encode_buffer(avctx, avpkt, s->frame_size, 0);
     if (ret < 0)
         return ret;
     ac3_output_frame(s, avpkt->data);

libavcodec/ac3enc_fixed.c

@@ -132,6 +132,7 @@ const AVCodec ff_ac3_fixed_encoder = {
     .long_name       = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
     .type            = AVMEDIA_TYPE_AUDIO,
     .id              = AV_CODEC_ID_AC3,
+    .capabilities    = AV_CODEC_CAP_DR1,
     .priv_data_size  = sizeof(AC3EncodeContext),
     .init            = ac3_fixed_encode_init,
     .encode2         = ff_ac3_fixed_encode_frame,

libavcodec/ac3enc_float.c

@@ -136,6 +136,7 @@ const AVCodec ff_ac3_encoder = {
     .long_name       = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
     .type            = AVMEDIA_TYPE_AUDIO,
     .id              = AV_CODEC_ID_AC3,
+    .capabilities    = AV_CODEC_CAP_DR1,
     .priv_data_size  = sizeof(AC3EncodeContext),
     .init            = ff_ac3_float_encode_init,
     .encode2         = ff_ac3_float_encode_frame,

libavcodec/eac3enc.c

@@ -253,6 +253,7 @@ const AVCodec ff_eac3_encoder = {
     .long_name       = NULL_IF_CONFIG_SMALL("ATSC A/52 E-AC-3"),
     .type            = AVMEDIA_TYPE_AUDIO,
     .id              = AV_CODEC_ID_EAC3,
+    .capabilities    = AV_CODEC_CAP_DR1,
     .priv_data_size  = sizeof(AC3EncodeContext),
     .init            = ff_ac3_float_encode_init,
     .encode2         = ff_ac3_float_encode_frame,