diff --git a/Changelog b/Changelog
index 80f72c91a7..5d02019758 100644
--- a/Changelog
+++ b/Changelog
@@ -33,6 +33,8 @@ version <next>
 - SFTP protocol (via libssh)
 - libx264: add ability to encode in YUVJ422P and YUVJ444P
 - Fraps: use BT.709 colorspace by default for yuv, as reference fraps decoder does
+- make decoding alpha optional for prores, ffv1 and vp6 by setting
+  the skip_alpha flag.
 
 
 version 2.0:
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 997a00cbf6..61048f4dcf 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -2865,6 +2865,19 @@ typedef struct AVCodecContext {
 #define FF_SUB_CHARENC_MODE_AUTOMATIC    0  ///< libavcodec will select the mode itself
 #define FF_SUB_CHARENC_MODE_PRE_DECODER  1  ///< the AVPacket data needs to be recoded to UTF-8 before being fed to the decoder, requires iconv
 
+    /**
+     * Skip processing alpha if supported by codec.
+     * Note that if the format uses pre-multiplied alpha (common with VP6,
+     * and recommended due to better video quality/compression)
+     * the image will look as if alpha-blended onto a black background.
+     * However for formats that do not use pre-multiplied alpha
+     * there might be serious artefacts (though e.g. libswscale currently
+     * assumes pre-multiplied alpha anyway).
+     *
+     * - decoding: set by user
+     * - encoding: unused
+     */
+    int skip_alpha;
 } AVCodecContext;
 
 AVRational av_codec_get_pkt_timebase         (const AVCodecContext *avctx);
diff --git a/libavcodec/ffv1dec.c b/libavcodec/ffv1dec.c
index 87cc2ca450..57a566bb62 100644
--- a/libavcodec/ffv1dec.c
+++ b/libavcodec/ffv1dec.c
@@ -641,6 +641,7 @@ static int read_header(FFV1Context *f)
     }
 
     if (f->colorspace == 0) {
+        if (f->avctx->skip_alpha) f->transparency = 0;
         if (!f->transparency && !f->chroma_planes) {
             if (f->avctx->bits_per_raw_sample <= 8)
                 f->avctx->pix_fmt = AV_PIX_FMT_GRAY8;
diff --git a/libavcodec/options_table.h b/libavcodec/options_table.h
index e9cdfc4ac4..8c025fe076 100644
--- a/libavcodec/options_table.h
+++ b/libavcodec/options_table.h
@@ -380,6 +380,7 @@ static const AVOption avcodec_options[] = {
 {"auto",        NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_SUB_CHARENC_MODE_AUTOMATIC},   INT_MIN, INT_MAX, S|D, "sub_charenc_mode"},
 {"pre_decoder", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = FF_SUB_CHARENC_MODE_PRE_DECODER}, INT_MIN, INT_MAX, S|D, "sub_charenc_mode"},
 {"refcounted_frames", NULL, OFFSET(refcounted_frames), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, A|V|D },
+{"skip_alpha", "Skip processing alpha", OFFSET(skip_alpha), AV_OPT_TYPE_INT, {.i64 = 0 }, 0, 1, V|D },
 {NULL},
 };
 
diff --git a/libavcodec/proresdec2.c b/libavcodec/proresdec2.c
index 9a8861cb22..4950652ed9 100644
--- a/libavcodec/proresdec2.c
+++ b/libavcodec/proresdec2.c
@@ -97,6 +97,7 @@ static int decode_frame_header(ProresContext *ctx, const uint8_t *buf,
         av_log(avctx, AV_LOG_ERROR, "Invalid alpha mode %d\n", ctx->alpha_info);
         return AVERROR_INVALIDDATA;
     }
+    if (avctx->skip_alpha) ctx->alpha_info = 0;
 
     av_dlog(avctx, "frame type %d\n", ctx->frame_type);
 
diff --git a/libavcodec/proresdec_lgpl.c b/libavcodec/proresdec_lgpl.c
index 2fef2c6e43..04aeb16ab5 100644
--- a/libavcodec/proresdec_lgpl.c
+++ b/libavcodec/proresdec_lgpl.c
@@ -140,6 +140,7 @@ static int decode_frame_header(ProresContext *ctx, const uint8_t *buf,
         av_log(avctx, AV_LOG_ERROR, "Invalid alpha mode %d\n", ctx->alpha_info);
         return AVERROR_INVALIDDATA;
     }
+    if (avctx->skip_alpha) ctx->alpha_info = 0;
 
     switch (ctx->chroma_factor) {
     case 2:
@@ -609,7 +610,7 @@ static int decode_slice(AVCodecContext *avctx, void *tdata)
     coff[2]     = coff[1] + u_data_size;
     v_data_size = hdr_size > 7 ? AV_RB16(buf + 6) : slice_data_size - coff[2];
     coff[3]     = coff[2] + v_data_size;
-    a_data_size = slice_data_size - coff[3];
+    a_data_size = ctx->alpha_info ? slice_data_size - coff[3] : 0;
 
     /* if V or alpha component size is negative that means that previous
        component sizes are too large */
diff --git a/libavcodec/vp56.c b/libavcodec/vp56.c
index 25801ea6c0..d67eaa6b0d 100644
--- a/libavcodec/vp56.c
+++ b/libavcodec/vp56.c
@@ -530,7 +530,7 @@ int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
     if (ff_get_buffer(avctx, p, AV_GET_BUFFER_FLAG_REF) < 0)
         return -1;
 
-    if (s->has_alpha) {
+    if (avctx->pix_fmt == AV_PIX_FMT_YUVA420P) {
         av_frame_unref(s->alpha_context->frames[VP56_FRAME_CURRENT]);
         if ((ret = av_frame_ref(s->alpha_context->frames[VP56_FRAME_CURRENT], p)) < 0) {
             av_frame_unref(p);
@@ -545,7 +545,7 @@ int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
         }
     }
 
-    if (s->has_alpha) {
+    if (avctx->pix_fmt == AV_PIX_FMT_YUVA420P) {
         int bak_w = avctx->width;
         int bak_h = avctx->height;
         int bak_cw = avctx->coded_width;
@@ -567,7 +567,7 @@ int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
         }
     }
 
-    avctx->execute2(avctx, ff_vp56_decode_mbs, 0, 0, s->has_alpha + 1);
+    avctx->execute2(avctx, ff_vp56_decode_mbs, 0, 0, (avctx->pix_fmt == AV_PIX_FMT_YUVA420P) + 1);
 
     if ((res = av_frame_ref(data, p)) < 0)
         return res;
@@ -690,6 +690,7 @@ av_cold int ff_vp56_init_context(AVCodecContext *avctx, VP56Context *s,
 
     s->avctx = avctx;
     avctx->pix_fmt = has_alpha ? AV_PIX_FMT_YUVA420P : AV_PIX_FMT_YUV420P;
+    if (avctx->skip_alpha) avctx->pix_fmt = AV_PIX_FMT_YUV420P;
 
     ff_h264chroma_init(&s->h264chroma, 8);
     ff_hpeldsp_init(&s->hdsp, avctx->flags);
diff --git a/tests/fate/prores.mak b/tests/fate/prores.mak
index c608aef6fc..716f4e3741 100644
--- a/tests/fate/prores.mak
+++ b/tests/fate/prores.mak
@@ -3,7 +3,9 @@ FATE_PRORES = fate-prores-422                                           \
               fate-prores-422_lt                                        \
               fate-prores-422_proxy                                     \
               fate-prores-alpha                                         \
+              fate-prores-alpha_skip                                    \
               fate-prores-transparency                                  \
+              fate-prores-transparency_skip                             \
 
 FATE_SAMPLES_AVCONV-$(call DEMDEC, MOV, PRORES) += $(FATE_PRORES)
 fate-prores: $(FATE_PRORES)
@@ -13,4 +15,6 @@ fate-prores-422_hq:    CMD = framecrc -flags +bitexact -i $(TARGET_SAMPLES)/pror
 fate-prores-422_lt:    CMD = framecrc -flags +bitexact -i $(TARGET_SAMPLES)/prores/Sequence_1-Apple_ProRes_422_LT.mov -pix_fmt yuv422p10le
 fate-prores-422_proxy: CMD = framecrc -flags +bitexact -i $(TARGET_SAMPLES)/prores/Sequence_1-Apple_ProRes_422_Proxy.mov -pix_fmt yuv422p10le
 fate-prores-alpha:     CMD = framecrc -flags +bitexact -i $(TARGET_SAMPLES)/prores/Sequence_1-Apple_ProRes_with_Alpha.mov -pix_fmt yuva444p10le
+fate-prores-alpha_skip: CMD = framecrc -flags +bitexact -skip_alpha 1 -i $(TARGET_SAMPLES)/prores/Sequence_1-Apple_ProRes_with_Alpha.mov
 fate-prores-transparency: CMD = framecrc -flags +bitexact -i $(TARGET_SAMPLES)/prores/prores4444_with_transparency.mov -pix_fmt yuva444p10le
+fate-prores-transparency_skip: CMD = framecrc -flags +bitexact -skip_alpha 1 -i $(TARGET_SAMPLES)/prores/prores4444_with_transparency.mov
diff --git a/tests/fate/vpx.mak b/tests/fate/vpx.mak
index ba53a2aa49..99a58559e4 100644
--- a/tests/fate/vpx.mak
+++ b/tests/fate/vpx.mak
@@ -19,6 +19,9 @@ fate-vp61: CMD = framecrc -flags +bitexact -i $(TARGET_SAMPLES)/ea-vp6/MovieSkir
 FATE_VP6-$(call DEMDEC, FLV, VP6A) += fate-vp6a
 fate-vp6a: CMD = framecrc -flags +bitexact -i $(TARGET_SAMPLES)/flash-vp6/300x180-Scr-f8-056alpha.flv
 
+FATE_VP6-$(call DEMDEC, FLV, VP6A) += fate-vp6a-skip_alpha
+fate-vp6a-skip_alpha: CMD = framecrc -flags +bitexact -skip_alpha 1 -i $(TARGET_SAMPLES)/flash-vp6/300x180-Scr-f8-056alpha.flv
+
 FATE_VP6-$(call DEMDEC, FLV, VP6F) += fate-vp6f
 fate-vp6f: CMD = framecrc -flags +bitexact -i $(TARGET_SAMPLES)/flash-vp6/clip1024.flv
 
diff --git a/tests/ref/fate/prores-alpha_skip b/tests/ref/fate/prores-alpha_skip
new file mode 100644
index 0000000000..bdb5c6ee70
--- /dev/null
+++ b/tests/ref/fate/prores-alpha_skip
@@ -0,0 +1,3 @@
+#tb 0: 100/2997
+0,          0,          0,        1, 12441600, 0x254d8f95
+0,          1,          1,        1, 12441600, 0x254d8f95
diff --git a/tests/ref/fate/prores-transparency_skip b/tests/ref/fate/prores-transparency_skip
new file mode 100644
index 0000000000..a2921a4e41
--- /dev/null
+++ b/tests/ref/fate/prores-transparency_skip
@@ -0,0 +1,5 @@
+#tb 0: 1/25
+#tb 1: 1/48000
+0,          0,          0,        1, 12441600, 0x58bff47d
+1,          0,          0,     1024,     4096, 0x00000000
+1,       1024,       1024,      896,     3584, 0x00000000
diff --git a/tests/ref/fate/vp6a-skip_alpha b/tests/ref/fate/vp6a-skip_alpha
new file mode 100644
index 0000000000..91a099c58b
--- /dev/null
+++ b/tests/ref/fate/vp6a-skip_alpha
@@ -0,0 +1,94 @@
+#tb 0: 1/4
+0,          0,          0,        1,    81000, 0xcb92962d
+0,          1,          1,        1,    81000, 0xae381904
+0,          2,          2,        1,    81000, 0x1fcc0c75
+0,          3,          3,        1,    81000, 0x023f0c21
+0,          4,          4,        1,    81000, 0xad691402
+0,          5,          5,        1,    81000, 0x42390be0
+0,          6,          6,        1,    81000, 0xc1c10a4e
+0,          7,          7,        1,    81000, 0x9c0315ac
+0,          8,          8,        1,    81000, 0xc2a315a7
+0,          9,          9,        1,    81000, 0x3a631392
+0,         10,         10,        1,    81000, 0x11591414
+0,         11,         11,        1,    81000, 0x1a551125
+0,         12,         12,        1,    81000, 0x2e1efa4f
+0,         13,         13,        1,    81000, 0x4aa3f016
+0,         14,         14,        1,    81000, 0x74c029d8
+0,         15,         15,        1,    81000, 0xdee9a98b
+0,         16,         16,        1,    81000, 0xdf3502d5
+0,         17,         17,        1,    81000, 0x4653536b
+0,         18,         18,        1,    81000, 0x7f658c75
+0,         19,         19,        1,    81000, 0xab18ff13
+0,         20,         20,        1,    81000, 0xac2b8f3b
+0,         21,         21,        1,    81000, 0xd61ff094
+0,         22,         22,        1,    81000, 0x425bfc2b
+0,         23,         23,        1,    81000, 0x6be7ecd3
+0,         24,         24,        1,    81000, 0x0b0ee65b
+0,         25,         25,        1,    81000, 0x3c6f146b
+0,         26,         26,        1,    81000, 0x27c4e9c8
+0,         27,         27,        1,    81000, 0x174022c4
+0,         28,         28,        1,    81000, 0x3320fe81
+0,         29,         29,        1,    81000, 0x7a3c342e
+0,         30,         30,        1,    81000, 0x448b4346
+0,         31,         31,        1,    81000, 0xd285b23d
+0,         32,         32,        1,    81000, 0x852ed590
+0,         33,         33,        1,    81000, 0xc9d3df17
+0,         34,         34,        1,    81000, 0x4d23727b
+0,         35,         35,        1,    81000, 0x1fae66cd
+0,         36,         36,        1,    81000, 0x384d54ab
+0,         37,         37,        1,    81000, 0x2fee6ba3
+0,         38,         38,        1,    81000, 0xd7ad6f59
+0,         39,         39,        1,    81000, 0xaf5e3e76
+0,         40,         40,        1,    81000, 0x10fceda4
+0,         41,         41,        1,    81000, 0xb26df92b
+0,         42,         42,        1,    81000, 0xd6676e08
+0,         43,         43,        1,    81000, 0xff6b1b95
+0,         44,         44,        1,    81000, 0x6196d598
+0,         45,         45,        1,    81000, 0x833ebf1b
+0,         46,         46,        1,    81000, 0x7b085af1
+0,         47,         47,        1,    81000, 0xe8f583b4
+0,         48,         48,        1,    81000, 0x3426d5e4
+0,         49,         49,        1,    81000, 0x214069ed
+0,         50,         50,        1,    81000, 0x7dbdfd3f
+0,         51,         51,        1,    81000, 0xf19b3f45
+0,         52,         52,        1,    81000, 0x0f05c7e2
+0,         53,         53,        1,    81000, 0xba94e323
+0,         54,         54,        1,    81000, 0x0de7b0c2
+0,         55,         55,        1,    81000, 0xfcf93c55
+0,         56,         56,        1,    81000, 0x8a8dbd55
+0,         57,         57,        1,    81000, 0xddf22b97
+0,         58,         58,        1,    81000, 0x49a830ff
+0,         59,         59,        1,    81000, 0x82ab2a4b
+0,         60,         60,        1,    81000, 0xd23420e5
+0,         61,         61,        1,    81000, 0x7c1017d1
+0,         62,         62,        1,    81000, 0x9aa61b38
+0,         63,         63,        1,    81000, 0x2a724a18
+0,         64,         64,        1,    81000, 0xc18055f2
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+0,         66,         66,        1,    81000, 0x0eed6b0f
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+0,         68,         68,        1,    81000, 0xa681214e
+0,         69,         69,        1,    81000, 0x4958f83d
+0,         70,         70,        1,    81000, 0xca0f0d61
+0,         71,         71,        1,    81000, 0x3c453de1
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+0,         73,         73,        1,    81000, 0xdcef0949
+0,         74,         74,        1,    81000, 0xe5e3732d
+0,         75,         75,        1,    81000, 0x39747fd4
+0,         76,         76,        1,    81000, 0x6bec70e6
+0,         77,         77,        1,    81000, 0x7026a8c0
+0,         78,         78,        1,    81000, 0x92de5b61
+0,         79,         79,        1,    81000, 0x3f00507f
+0,         80,         80,        1,    81000, 0x5620c377
+0,         81,         81,        1,    81000, 0x39f5ed38
+0,         82,         82,        1,    81000, 0x6ee35d67
+0,         83,         83,        1,    81000, 0x4f99a409
+0,         84,         84,        1,    81000, 0x0a05b6ea
+0,         85,         85,        1,    81000, 0xd6c442d9
+0,         86,         86,        1,    81000, 0x0bb3d2f0
+0,         87,         87,        1,    81000, 0x6891c5b1
+0,         88,         88,        1,    81000, 0xf16ba9be
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