From c9ec824211cccb745b3a4ab014d6be726c8ef1b9 Mon Sep 17 00:00:00 2001
From: Paul B Mahol <onemda@gmail.com>
Date: Tue, 31 Jan 2023 10:18:17 +0100
Subject: [PATCH] avcodec: add media100_to_mjpegb bitstream filter and use it

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 libavcodec/Makefile                           |   3 +-
 libavcodec/bitstream_filters.c                |   1 +
 .../{media100.c => media100_to_mjpegb_bsf.c}  | 112 +++++++-----------
 libavcodec/mjpegbdec.c                        |  15 +++
 4 files changed, 61 insertions(+), 70 deletions(-)
 rename libavcodec/{media100.c => media100_to_mjpegb_bsf.c} (65%)

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index df76d37598..4971832ff4 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -485,7 +485,7 @@ OBJS-$(CONFIG_MACE6_DECODER)           += mace.o
 OBJS-$(CONFIG_MAGICYUV_DECODER)        += magicyuv.o
 OBJS-$(CONFIG_MAGICYUV_ENCODER)        += magicyuvenc.o
 OBJS-$(CONFIG_MDEC_DECODER)            += mdec.o mpeg12.o mpeg12data.o
-OBJS-$(CONFIG_MEDIA100_DECODER)        += media100.o
+OBJS-$(CONFIG_MEDIA100_DECODER)        += mjpegbdec.o
 OBJS-$(CONFIG_METASOUND_DECODER)       += metasound.o twinvq.o
 OBJS-$(CONFIG_MICRODVD_DECODER)        += microdvddec.o ass.o
 OBJS-$(CONFIG_MIMIC_DECODER)           += mimic.o
@@ -1221,6 +1221,7 @@ OBJS-$(CONFIG_HEVC_METADATA_BSF)          += h265_metadata_bsf.o h265_profile_le
                                              h2645data.o
 OBJS-$(CONFIG_HEVC_MP4TOANNEXB_BSF)       += hevc_mp4toannexb_bsf.o
 OBJS-$(CONFIG_IMX_DUMP_HEADER_BSF)        += imx_dump_header_bsf.o
+OBJS-$(CONFIG_MEDIA100_TO_MJPEGB_BSF)     += media100_to_mjpegb_bsf.o
 OBJS-$(CONFIG_MJPEG2JPEG_BSF)             += mjpeg2jpeg_bsf.o
 OBJS-$(CONFIG_MJPEGA_DUMP_HEADER_BSF)     += mjpega_dump_header_bsf.o
 OBJS-$(CONFIG_MPEG4_UNPACK_BFRAMES_BSF)   += mpeg4_unpack_bframes_bsf.o
diff --git a/libavcodec/bitstream_filters.c b/libavcodec/bitstream_filters.c
index a3bebefe5f..e8216819ca 100644
--- a/libavcodec/bitstream_filters.c
+++ b/libavcodec/bitstream_filters.c
@@ -43,6 +43,7 @@ extern const FFBitStreamFilter ff_hapqa_extract_bsf;
 extern const FFBitStreamFilter ff_hevc_metadata_bsf;
 extern const FFBitStreamFilter ff_hevc_mp4toannexb_bsf;
 extern const FFBitStreamFilter ff_imx_dump_header_bsf;
+extern const FFBitStreamFilter ff_media100_to_mjpegb_bsf;
 extern const FFBitStreamFilter ff_mjpeg2jpeg_bsf;
 extern const FFBitStreamFilter ff_mjpega_dump_header_bsf;
 extern const FFBitStreamFilter ff_mp3_header_decompress_bsf;
diff --git a/libavcodec/media100.c b/libavcodec/media100_to_mjpegb_bsf.c
similarity index 65%
rename from libavcodec/media100.c
rename to libavcodec/media100_to_mjpegb_bsf.c
index 37b98c9a57..dafb65a0ad 100644
--- a/libavcodec/media100.c
+++ b/libavcodec/media100_to_mjpegb_bsf.c
@@ -1,6 +1,6 @@
 /*
- * Media 100 decoder
- * Copyright (c) 2022 Paul B Mahol
+ * Media 100 to MJPEGB bitstream filter
+ * Copyright (c) 2023 Paul B Mahol
  *
  * This file is part of FFmpeg.
  *
@@ -21,55 +21,34 @@
 
 /**
  * @file
- * Media 100 decoder.
+ * Media 100 to MJPEGB bitstream filter.
  */
 
 #include <inttypes.h>
 
+#include "bsf.h"
+#include "bsf_internal.h"
 #include "libavutil/intreadwrite.h"
-#include "avcodec.h"
 #include "bytestream.h"
-#include "codec_internal.h"
 
 typedef struct Media100Context {
-    AVCodecContext *avctx;   // wrapper context for mjpegb
     AVPacket *pkt;
 } Media100Context;
 
-static av_cold int media100_decode_init(AVCodecContext *avctx)
+static av_cold int init(AVBSFContext *ctx)
 {
-    Media100Context *ctx = avctx->priv_data;
-    const AVCodec *codec;
-    int ret;
-
-    codec = avcodec_find_decoder(AV_CODEC_ID_MJPEGB);
-    if (!codec)
-        return AVERROR_BUG;
-    ctx->avctx = avcodec_alloc_context3(codec);
-    if (!ctx->avctx)
-        return AVERROR(ENOMEM);
-    ctx->avctx->thread_count = 1;
-    ctx->avctx->flags  = avctx->flags;
-    ctx->avctx->flags2 = avctx->flags2;
-    ctx->avctx->width  = ctx->avctx->coded_width  = avctx->width;
-    ctx->avctx->height = ctx->avctx->coded_height = avctx->height;
-
-    ret = avcodec_open2(ctx->avctx, codec, NULL);
-    if (ret < 0)
-        return ret;
+    Media100Context *s = ctx->priv_data;
 
-    ctx->pkt = av_packet_alloc();
-    if (!ctx->pkt)
+    s->pkt = av_packet_alloc();
+    if (!s->pkt)
         return AVERROR(ENOMEM);
 
     return 0;
 }
 
-static int media100_decode_frame(AVCodecContext *avctx,
-                                 AVFrame *frame, int *got_frame,
-                                 AVPacket *avpkt)
+static int filter(AVBSFContext *ctx, AVPacket *avpkt)
 {
-    Media100Context *ctx = avctx->priv_data;
+    Media100Context *s = ctx->priv_data;
     unsigned second_field_offset = 0;
     unsigned next_field = 0;
     unsigned dht_offset[2];
@@ -83,18 +62,20 @@ static int media100_decode_frame(AVCodecContext *avctx,
     AVPacket *pkt;
     int ret;
 
-    if (avpkt->size + 1024 > ctx->pkt->size) {
-        ret = av_grow_packet(ctx->pkt, avpkt->size + 1024 - ctx->pkt->size);
-        if (ret < 0)
-            return ret;
-    }
+    ret = ff_bsf_get_packet_ref(ctx, avpkt);
+    if (ret < 0)
+        return ret;
 
-    ret = av_packet_make_writable(ctx->pkt);
+    ret = av_new_packet(s->pkt, avpkt->size + 1024);
+    if (ret < 0)
+        return ret;
+
+    ret = av_packet_make_writable(s->pkt);
     if (ret < 0)
         return ret;
 
     bytestream2_init(&gb, avpkt->data, avpkt->size);
-    bytestream2_init_writer(&pb, ctx->pkt->data, ctx->pkt->size);
+    bytestream2_init_writer(&pb, s->pkt->data, s->pkt->size);
 
 second_field:
     bytestream2_put_be32(&pb, 0);
@@ -107,8 +88,8 @@ second_field:
     sof_offset[field] = bytestream2_tell_p(&pb);
     bytestream2_put_be16(&pb, 17);
     bytestream2_put_byte(&pb, 8);
-    bytestream2_put_be16(&pb, avctx->height / 2);
-    bytestream2_put_be16(&pb, avctx->width);
+    bytestream2_put_be16(&pb, ctx->par_in->height / 2);
+    bytestream2_put_be16(&pb, ctx->par_in->width);
     bytestream2_put_byte(&pb, 3);
     bytestream2_put_byte(&pb, 1);
     bytestream2_put_byte(&pb, 0x21);
@@ -164,7 +145,7 @@ second_field:
         goto second_field;
     }
 
-    pkt = ctx->pkt;
+    pkt = s->pkt;
 
     AV_WB32(pkt->data +  8, second_field_offset);
     AV_WB32(pkt->data + 12, second_field_offset);
@@ -186,40 +167,33 @@ second_field:
 
     pkt->size = bytestream2_tell_p(&pb);
 
-    ret = avcodec_send_packet(ctx->avctx, pkt);
-    if (ret < 0) {
-        av_log(avctx, AV_LOG_ERROR, "Error submitting a packet for decoding\n");
-        return ret;
-    }
+    av_packet_copy_props(pkt, avpkt);
+    av_packet_unref(avpkt);
+    av_packet_move_ref(avpkt, s->pkt);
 
-    ret = avcodec_receive_frame(ctx->avctx, frame);
-    if (ret < 0)
-        return ret;
+    return 0;
+}
 
-    avctx->pix_fmt = ctx->avctx->pix_fmt;
-    *got_frame = 1;
+static void flush(AVBSFContext *ctx)
+{
+    Media100Context *s = ctx->priv_data;
 
-    return avpkt->size;
+    av_packet_unref(s->pkt);
 }
 
-static av_cold int media100_decode_end(AVCodecContext *avctx)
+static av_cold void uninit(AVBSFContext *ctx)
 {
-    Media100Context *ctx = avctx->priv_data;
+    Media100Context *s = ctx->priv_data;
 
-    avcodec_free_context(&ctx->avctx);
-    av_packet_free(&ctx->pkt);
-
-    return 0;
+    av_packet_free(&s->pkt);
 }
 
-const FFCodec ff_media100_decoder = {
-    .p.name           = "media100",
-    CODEC_LONG_NAME("Media 100"),
-    .p.type           = AVMEDIA_TYPE_VIDEO,
-    .p.id             = AV_CODEC_ID_MEDIA100,
-    .priv_data_size   = sizeof(Media100Context),
-    .init             = media100_decode_init,
-    .close            = media100_decode_end,
-    FF_CODEC_DECODE_CB(media100_decode_frame),
-    .caps_internal    = FF_CODEC_CAP_INIT_CLEANUP,
+const FFBitStreamFilter ff_media100_to_mjpegb_bsf = {
+    .p.name         = "media100_to_mjpegb",
+    .p.codec_ids    = (const enum AVCodecID []){ AV_CODEC_ID_MEDIA100, AV_CODEC_ID_NONE },
+    .priv_data_size = sizeof(Media100Context),
+    .init           = init,
+    .flush          = flush,
+    .close          = uninit,
+    .filter         = filter,
 };
diff --git a/libavcodec/mjpegbdec.c b/libavcodec/mjpegbdec.c
index 6d422e7a29..4db1d9a89d 100644
--- a/libavcodec/mjpegbdec.c
+++ b/libavcodec/mjpegbdec.c
@@ -168,3 +168,18 @@ const FFCodec ff_mjpegb_decoder = {
     .p.max_lowres   = 3,
     .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
 };
+
+const FFCodec ff_media100_decoder = {
+    .p.name         = "media100",
+    CODEC_LONG_NAME("Media 100"),
+    .p.type         = AVMEDIA_TYPE_VIDEO,
+    .p.id           = AV_CODEC_ID_MEDIA100,
+    .priv_data_size = sizeof(MJpegDecodeContext),
+    .init           = ff_mjpeg_decode_init,
+    .close          = ff_mjpeg_decode_end,
+    FF_CODEC_DECODE_CB(mjpegb_decode_frame),
+    .p.capabilities = AV_CODEC_CAP_DR1,
+    .p.max_lowres   = 3,
+    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
+    .bsfs           = "media100_to_mjpegb",
+};
-- 
2.39.1

