The following table should contain all the file formats FFmpeg currently supports, along with audio/video codecs each format supports. The table should help distinguish which codecs can be put inside which formats.

The columns are the following:
Format name - The formal name of the format.
FFmpeg format - The name of the format as used by FFmpeg tool. The list of all supported formats can be viewed using "ffmpeg -formats"
Codec name - The formal name of the codec.
FFmpeg codec - The name of the codec (enCODer/DECoder) as used by FFmpeg tool. The list of all supported codecs can be viewed using "ffmpeg -codecs"
Comment - A free form text comment.

Video

Format name	FFmpeg format	Codec name	FFmpeg codec	Comment
FLV	flv	Sorenson Spark	flv	Sorenson H.263
FLV	flv	H.263	h263	ITU-T VCEG H.263
FLV	flv	MPEG-4	mpeg4	MPEG-4 Part 2 ASP
FLV	flv	Screen Video	flashsv	Flash Screen Video
FLV	flv	Screen Video 2	flashsv2	Flash Screen Video Version 2
FLV	flv	VP6	remuxing only	On2 VP6
FLV	flv	VP6A	remuxing only	On2 VP6 with transparency support
FLV	flv	H.264	libx264	MPEG-4 Part 10 AVC, needs the external encoder library libx264

Audio

Format name	FFmpeg format	Codec name	FFmpeg codec	Comment
FLV	flv	MP3	libmp3lame	needs the external encoder library lame
FLV	flv	PCM U8	pcm_u8	8-bit pulse-code modulation
FLV	flv	PCM S16 BE	pcm_s16be	16-bit big-endian pulse-code modulation
FLV	flv	PCM S16 LE	pcm_s16le	16 bit little-endian pulse-code modulation
FLV	flv	ADPCM	adpcm_swf	Shockwave Flash Audio
FLV	flv	AAC	aac / libvo_aacenc / libfaac / libfdk_aac / libaacplus	FFmpeg's internal aac encoder/decoder (experimental), external libraries libvo_aacenc and libfaac are used to encode AAC-LC audio. libaacplus library is used to encode  HE-AAC v2 audio known as AAC+. libfdk_aac supports LC-AAC, HE-AAC, and HE-AAC v2.
FLV	flv	Asao	nellymoser	Nellymoser audio codec
FLV	flv	Speex	libspeex	needs the external encoder library libspeex